G Geometry and measures — coverage pack
25 specification leaves · notes, questions, answers and worked methods
G1 · Use conventional terms/notations: points, lines, vertices, edges, planes, parallel and perpendicular lines, right angles, polygons; standard triangle labelling; draw diagrams from written description
- Use precise geometric language: a vertex is a corner, an edge joins vertices, parallel lines never meet, and perpendicular lines meet at a right angle.
- Label an angle by placing its vertex in the middle, so is the angle at ; in triangle , side is opposite vertex .
- Build a diagram one instruction at a time, marking equal lengths, parallel lines and right angles with conventional symbols rather than relying on appearance.
- A common error is to assume a sketch is drawn to scale; only stated facts and marked relationships may be used.
Tier 1 · Easy
1. In triangle , which vertex is opposite the side ?[1 mark]
Answer
- Vertex
Method: The side joins vertices and . The remaining vertex is , so is opposite .
Tier 2 · Standard
1. Lines and are parallel. A line through meets at at a right angle. State the relationship between and .[1 mark]
Answer
- is perpendicular to .
Method: Because , a line perpendicular to is also perpendicular to . Therefore .
Tier 3 · Hard
1. Draw quadrilateral with . Draw diagonal . Mark a point on , then draw the line through perpendicular to , meeting at and at .[3 marks]
Answer
- A correctly labelled diagram with , collinear, collinear, and right-angle marks at and .
Method: Draw and arrow-mark the parallel sides and , then join to . Place on . Through , draw one straight line meeting at and at , and mark both perpendicular intersections as right angles.
G2 · Use standard ruler and compass constructions (perpendicular bisector, perpendicular from/at a point, angle bisector); construct figures, solve loci problems; perpendicular distance is shortest
- A perpendicular bisector crosses a segment at its midpoint at ; every point on it is equidistant from the segment's endpoints.
- Construct an angle bisector using equal-radius arcs from the vertex and then intersecting arcs from the two arms; points on it are equidistant from the arms.
- Translate locus conditions into standard boundaries: a fixed distance from a point gives a circle, while a fixed distance from a straight line gives two parallel lines.
- Keep compass arcs visible and do not measure to replace a construction; the perpendicular distance to a line is the shortest distance.
Tier 1 · Easy
1. Describe how to construct the perpendicular bisector of a line segment using a ruler and compasses.[2 marks]
Answer
- Draw equal-radius arcs from and that meet above and below , then join the two arc intersections.
Method: Set the compass radius to more than half of . Without changing it, draw arcs centred at and so that they intersect twice. A straight line through the intersections is the perpendicular bisector of .
Tier 2 · Standard
1. Two straight paths meet at . A lamp must be equally distant from the two paths and no more than m from . Describe the locus of possible positions inside the angle between the paths.[3 marks]
Answer
- The part of the internal angle bisector from up to and including the point m from .
Method: Points equidistant from two intersecting lines lie on an angle bisector. Restricting the distance from to at most m keeps only the segment of the internal bisector inside the circle centred at with radius m.
Tier 3 · Hard
1. Points and are cm apart. A point must satisfy and cm. Describe and construct the complete locus of .[4 marks]
Answer
- The part of the perpendicular bisector of lying inside or on both circles of radius cm centred at and ; it is the segment joining the circles' two intersection points.
Method: Construct the perpendicular bisector of because . Draw circles of radius cm centred at and . The condition keeps points inside both circles, so the required locus is the perpendicular-bisector segment between their two intersections.
G3 · Apply angles at a point, on a straight line, vertically opposite angles; use alternate and corresponding angles on parallel lines; derive and use the angle sum of a triangle and of any polygon
- Angles at a point sum to , angles on a straight line sum to , and vertically opposite angles are equal.
- When a transversal crosses parallel lines, alternate and corresponding angles are equal; co-interior angles sum to .
- Splitting an -sided polygon into triangles gives an interior-angle sum of .
- Do not quote alternate or corresponding angles unless the relevant lines are stated or shown to be parallel, and name the angle fact used.
Tier 1 · Easy
1. Two adjacent angles on a straight line are and . Work out .[1 mark]
Answer
Method: Angles on a straight line total , so .
Tier 2 · Standard
1. Two parallel lines are crossed by a transversal. A pair of alternate angles are and . Find and the size of these angles.[3 marks]
Answer
Method: Alternate angles between parallel lines are equal, so . Hence and . Substitution gives .
Tier 3 · Hard
1. A polygon has sides. Twelve of its interior angles are each . Work out the remaining interior angle.[4 marks]
Answer
Method: The interior-angle sum is . The twelve known angles total . The remaining angle is .
G4 · Derive and apply properties and definitions of special quadrilaterals (square, rectangle, parallelogram, trapezium, kite, rhombus), triangles and other plane figures using appropriate language
- Classify a shape from properties that must always hold: for example, a parallelogram has two pairs of parallel opposite sides and a trapezium has one pair of parallel sides.
- A rectangle has four right angles, a rhombus has four equal sides, and a square satisfies both definitions as well as being a parallelogram.
- Use diagonal properties carefully: parallelogram diagonals bisect each other, rectangle diagonals are also equal, and rhombus diagonals are also perpendicular.
- A common error is to use a property that is merely possible rather than guaranteed; one diagram cannot establish a definition.
Tier 1 · Easy
1. Name the quadrilateral that has exactly one pair of parallel sides.[1 mark]
Answer
- Trapezium
Method: A quadrilateral with exactly one pair of parallel sides is a trapezium.
Tier 2 · Standard
1. One interior angle of a rhombus is . Work out the other three interior angles.[2 marks]
Answer
- , ,
Method: Opposite angles in a rhombus are equal and adjacent angles sum to . The opposite angle is , and each adjacent angle is .
Tier 3 · Hard
1. The diagonals of quadrilateral bisect each other and are equal in length. Explain why must be a rectangle, and why the information does not prove that it is a square.[3 marks]
Answer
- Diagonals that bisect each other make the quadrilateral a parallelogram; equal diagonals then make it a rectangle. A square would additionally require four equal sides or perpendicular diagonals, which has not been given.
Method: First use the converse parallelogram property: diagonals that bisect each other establish a parallelogram. In a parallelogram, equal diagonals establish a rectangle. Equal diagonals alone do not establish equal sides or perpendicular diagonals, so a non-square rectangle remains possible.
G5 · Use the basic congruence criteria for triangles (SSS, SAS, ASA, RHS)
- Congruent triangles are identical in size and shape, so all corresponding sides and angles are equal.
- Use SSS for three side pairs, SAS for two side pairs and the included angle, ASA for two angle pairs and a side, and RHS for right triangles with equal hypotenuse and one other side.
- Write vertices in corresponding order when stating congruence, then transfer only matching sides or angles.
- AAA proves similarity, not congruence, and SSA is not a valid general congruence test.
Tier 1 · Easy
1. Triangle has side lengths cm, cm and cm. Triangle has side lengths cm, cm and cm. State the congruence criterion.[1 mark]
Answer
- SSS
Method: All three side lengths of one triangle match all three side lengths of the other, so the criterion is SSS.
Tier 2 · Standard
1. Triangles and are right-angled at and . Also cm and cm. Explain why the triangles are congruent.[2 marks]
Answer
- They are congruent by RHS.
Method: Both triangles are right-angled, their hypotenuses and are equal, and one corresponding pair of shorter sides and is equal. Therefore the triangles are congruent by RHS.
Tier 3 · Hard
1. In quadrilateral , diagonal is drawn. Given that and , prove that .[3 marks]
Answer
Method: Compare triangles and . We have , is common, and the included angles and are equal. The triangles are congruent by SAS, so corresponding sides and are equal.
G6 · Apply angle facts, congruence, similarity and quadrilateral properties to derive results about angles and sides, incl. Pythagoras' theorem and isosceles base angles, and obtain simple proofs
- In an isosceles triangle, equal sides face equal angles; the converse also holds, so equal angles face equal sides.
- For a right-angled triangle, use with opposite the right angle, and take the positive square root for a length.
- A geometric proof should form a connected chain in which every equality follows from a stated angle fact, shape property, similarity or congruence result.
- Do not use the fact being proved as a reason, and do not infer equal sides or angles just because they look equal in a sketch.
Tier 1 · Easy
1. Triangle is isosceles with . Angle is . Work out angle .[2 marks]
Answer
Method: Equal sides face equal angles, so angle is also . The angles in a triangle sum to , giving .
Tier 2 · Standard
1. A right-angled triangle has perpendicular sides cm and cm. Work out the length of its hypotenuse.[3 marks]
Answer
- cm
Method: By Pythagoras' theorem, . Therefore cm.
Tier 3 · Hard
1. In quadrilateral , and . Diagonal is drawn. Prove that .[4 marks]
Answer
Method: Because , as alternate angles. Also and is common. Thus triangles and are congruent by SAS. Corresponding sides and are therefore equal.
G7 · Identify, describe and construct congruent and similar shapes, incl. on coordinate axes, by rotation, reflection, translation and enlargement (including fractional and negative scale factors)
- Describe a translation by a vector, a rotation by its centre, angle and direction, a reflection by its mirror line, and an enlargement by its centre and scale factor.
- Translations, rotations and reflections preserve lengths and angles, so the image is congruent to the object; an enlargement preserves angles and scales every length by the same factor.
- For an enlargement about centre , multiply the vector from to each point by the scale factor; a negative factor places the image on the opposite side of .
- A common error is to omit part of a full transformation description or to multiply coordinates directly when the centre of enlargement is not the origin.
Tier 1 · Easy
1. Point is translated by the vector . Find the coordinates of its image.[2 marks]
Answer
Method: Add the vector components to the coordinates: .
Tier 2 · Standard
1. Point is rotated anticlockwise about the origin. Find the coordinates of its image .[2 marks]
Answer
Method: A anticlockwise rotation about the origin maps to . Therefore maps to .
Tier 3 · Hard
1. Triangle has vertices , and . It is enlarged by scale factor about centre . Find the three image coordinates.[4 marks]
Answer
Method: Subtract the centre, multiply by , then add the centre. For , , giving . For , , giving . For , , giving .
G8 · Describe the changes and invariance achieved by combinations of rotations, reflections and translations [Higher only]
- Track a combination in the stated order: the output of the first transformation is the input to the next.
- Two translations combine by adding their vectors, while some pairs of reflections combine to form a rotation or a translation.
- Rotations, reflections and translations preserve lengths, angle sizes, area and parallelism; reflections reverse orientation, whereas rotations and translations preserve it.
- Do not reverse the order of a combination: transformations need not commute, so changing the order can change the final image.
Tier 1 · Easy
1. A shape is rotated and then translated. State two properties of the shape that must remain invariant.[2 marks]
Answer
- Any two of: side lengths, angle sizes, area, parallelism, or orientation remain unchanged.
Method: Both a rotation and a translation are rigid transformations. Each preserves lengths and angles, so it also preserves area and parallel lines; neither reverses orientation.
Tier 2 · Standard
1. A shape is translated first by and then by . Describe the single equivalent transformation.[2 marks]
Answer
- A translation by .
Method: Add the translation vectors component by component: .
Tier 3 · Hard
1. A shape is reflected in the -axis and then reflected in the line . Describe the single equivalent transformation and state whether orientation is preserved.[4 marks]
Answer
- A rotation of anticlockwise about the origin; orientation is preserved.
Method: The first reflection maps to . Reflection in then swaps the coordinates, giving . This is the coordinate rule for a anticlockwise rotation about the origin. A rotation preserves orientation.
G9 · Identify and apply circle definitions and properties, including: centre, radius, chord, diameter, circumference, tangent, arc, sector and segment
- A radius joins the centre to the circumference, a diameter is a chord through the centre, and every diameter is twice the radius.
- A tangent touches a circle at one point, while a chord joins two points on the circumference; an arc is a portion of the circumference.
- A sector is bounded by two radii and an arc, whereas a segment is bounded by a chord and an arc.
- Do not call the curved boundary a circle: the circumference is the boundary, while the circle includes the region inside it.
Tier 1 · Easy
1. A circle has radius cm. Write down its diameter.[1 mark]
Answer
- cm
Method: The diameter is twice the radius, so cm.
Tier 2 · Standard
1. A straight segment joins two points on a circle but does not pass through its centre. Another straight line meets the circle at exactly one point. Give the geometric name of each.[2 marks]
Answer
- The segment is a chord; the line is a tangent.
Method: A segment whose endpoints lie on the circumference is a chord. A line meeting a circle at exactly one point is a tangent.
Tier 3 · Hard
1. A circle is centred at . Distinct points and are on its circumference, and is not a diameter. Describe precisely the boundaries of the minor sector and the minor segment cut off by .[3 marks]
Answer
- The minor sector is bounded by radii and and the minor arc ; the minor segment is bounded by chord and the minor arc .
Method: A sector uses two radii plus their connecting arc. A segment uses a chord plus its corresponding arc. Selecting the shorter arc gives the minor sector and minor segment.
G10 · Apply and prove the standard circle theorems concerning angles, radii, tangents and chords, and use them to prove related results [Higher only]
- The angle at the centre is twice the angle at the circumference standing on the same arc; angles in the same segment are equal, and an angle in a semicircle is .
- Opposite angles in a cyclic quadrilateral sum to , and the alternate segment theorem links the angle between a tangent and chord to the angle in the opposite segment.
- A radius is perpendicular to a tangent at the point of contact; tangents from the same external point are equal, and the perpendicular from the centre bisects a chord.
- Always identify the same chord or arc before applying an angle theorem, and state the theorem as the reason rather than quoting an unsupported angle.
Tier 1 · Easy
1. is a diameter of a circle and is another point on the circumference. Find .[1 mark]
Answer
Method: The angle in a semicircle is , so .
Tier 2 · Standard
1. In a circle with centre , the angle is . Point lies on the major arc . Work out .[2 marks]
Answer
Method: Both angles stand on the minor arc . The angle at the centre is twice the angle at the circumference, so .
Tier 3 · Hard
1. From a point outside a circle with centre , tangents touch the circle at and . Prove that and that bisects .[4 marks]
Answer
- and
Method: Radii meet tangents at right angles, so triangles and are right-angled. They have equal hypotenuse and equal radii , so they are congruent by RHS. Corresponding parts then give and , proving that bisects .
G11 · Solve geometrical problems on coordinate axes
- Use coordinate differences to find horizontal and vertical lengths, and use the midpoint formula by averaging the two -coordinates and the two -coordinates.
- The distance between and is by Pythagoras' theorem.
- Gradients can establish geometry: equal gradients show parallel lines, while gradients with product show perpendicular non-vertical lines.
- Keep signs when subtracting negative coordinates, and do not read a length directly from a sketch that is not drawn to scale.
Tier 1 · Easy
1. Find the midpoint of the line segment joining to .[2 marks]
Answer
Method: Average the coordinates: and . The midpoint is .
Tier 2 · Standard
1. Points and are joined. Find the exact length .[3 marks]
Answer
Method: The coordinate changes are and . Therefore .
Tier 3 · Hard
1. Triangle has vertices , and . Show that the triangle is right-angled and isosceles, then work out its area.[5 marks]
Answer
- Right-angled at
- Area square units
Method: The gradients are and , whose product is , so the angle at is . Also and , so the triangle is isosceles. Its perpendicular equal sides have area square units.
G12 · Identify properties of the faces, surfaces, edges and vertices of: cubes, cuboids, prisms, cylinders, pyramids, cones and spheres
- A face is flat, a curved surface is not a face, an edge is where surfaces meet, and a vertex is a point where edges meet.
- An -sided prism has two congruent polygonal ends and rectangular side faces, giving faces, edges and vertices.
- A pyramid has one polygonal base and triangular faces meeting at one apex; a cone has one circular base, one curved surface and one vertex.
- Count each feature once, especially hidden edges, and do not give a sphere or cylinder vertices where no edges meet.
Tier 1 · Easy
1. Write down the number of faces and the number of vertices of a triangular prism.[2 marks]
Answer
- faces
- vertices
Method: A triangular prism has two triangular faces and three rectangular faces, making faces. Its two triangular ends have vertices.
Tier 2 · Standard
1. A solid has one circular plane face, one curved surface, one circular edge and one vertex. Name the solid.[2 marks]
Answer
- Cone
Method: The circular base is the one plane face, its rim is the circular edge, the side is curved, and the surfaces meet at one apex. These are the properties of a cone.
Tier 3 · Hard
1. A prism has a regular -sided polygon as each end. Work out its numbers of faces, edges and vertices.[3 marks]
Answer
- faces
- edges
- vertices
Method: For an -sided prism, the counts are faces, edges and vertices. With , these are faces, edges and vertices.
G13 · Construct and interpret plans and elevations of 3D shapes
- A plan is the view from directly above; a front or side elevation is an orthographic view from the stated horizontal direction.
- Project corresponding corners with parallel construction lines so widths align between the plan and front elevation and depths align between the plan and side elevation.
- For stacks of cubes, an elevation shows the greatest height visible in each column along that viewing direction, while a numbered plan records each stack height.
- Do not add perspective or show hidden internal edges unless asked; plans and elevations use true lengths in their viewing plane.
Tier 1 · Easy
1. A cuboid is cm long, cm wide and cm high. State the shape and dimensions of its plan.[2 marks]
Answer
- A rectangle cm by cm
Method: The plan is viewed from above, so it shows length and width but not height. Therefore it is an cm by cm rectangle.
Tier 2 · Standard
1. A numbered plan of unit-cube stacks has two rows. From north to south, the rows are and , with entries ordered west to east. Give the visible column heights in the front elevation viewed from the south and in the side elevation viewed from the east.[3 marks]
Answer
- Front elevation, west to east:
- Side elevation, north to south:
Method: From the south, take the greatest height in each west-east column: west gives and east gives . From the east, take the greatest height in each north-south row: north gives and south gives .
Tier 3 · Hard
1. A solid uses vertical stacks of unit cubes on all four cells of a by plan. Its front elevation viewed from the south has heights from west to east. Its side elevation viewed from the east has heights from north to south. Find the least possible number of cubes and give one numbered plan that achieves it.[4 marks]
Answer
- cubes; for example, from north to south the plan rows can be and , with entries west to east.
Method: The height required in both the west front column and south side row can be placed in the south-west cell. The height required in both the east front column and north side row can be placed in the north-east cell. The other two occupied cells need at least one cube each, giving . The plan rows and have exactly the stated elevations.
G14 · Use standard units of measure and related concepts (length, area, volume/capacity, mass, time, money, etc.)
- Standard units include millimetres, centimetres, metres and kilometres for length; square or cubic units for area and volume; litres for capacity; grams or kilograms for mass; and seconds, minutes or hours for time.
- Convert every measurement to compatible units before calculating, remembering that area conversion factors are squared and volume conversion factors are cubed.
- For example, because , it follows that and .
- A common error is to use the linear conversion factor for an area or volume, such as multiplying square metres by instead of to obtain square centimetres.
Tier 1 · Easy
1. Convert to grams.[1 mark]
Answer
Method: There are in , so . Therefore the mass is .
Tier 2 · Standard
1. A rectangular water tank is long, wide and high. It is full. Work out the volume of water in litres.[3 marks]
Answer
- litres
Method: The full volume is . The water occupies . Since litres, the volume is litres.
Tier 3 · Hard
1. A floor measures by . Square tiles have side length and are sold in boxes of . A decorator buys at least more tiles than the exact number needed. Each box costs £. Work out the total cost.[5 marks]
Answer
- £
Method: Each tile has side , so its area is . The floor area is , requiring exactly tiles. Including gives , so at least tiles are needed. Since , the decorator must buy boxes. The cost is , so the total is £.
G15 · Measure line segments and angles in geometric figures, including interpreting maps and scale drawings and use of bearings
- Lengths and angles can be measured from an accurate drawing, while a map scale links a measured map distance to the corresponding real distance.
- For a scale , multiply a map length by to obtain the real length in the same units; bearings are measured clockwise from north and written using three figures.
- For example, a clockwise angle of from north is written as the bearing , and the reverse bearing is .
- A common error is to measure a bearing anticlockwise or from an east-west line instead of clockwise from the north line at the starting point.
Tier 1 · Easy
1. A ray from point makes an angle of clockwise from north. Write its bearing from .[1 mark]
Answer
Method: A bearing is the clockwise angle from north written with three figures. Therefore is written as .
Tier 2 · Standard
1. On a map with north at the top, point is east and north of point . The scale is . Work out the real straight-line distance from to and the bearing of from . Give the bearing to the nearest degree.[4 marks]
Answer
Method: The map distance is . The real distance is . If the bearing angle is , then , so . Written as a three-figure bearing to the nearest degree, this is .
Tier 3 · Hard
1. On a scale drawing, a road of actual length is represented by a line long. Find the scale in the form . Another road is long on the same drawing. Work out its actual length in kilometres.[4 marks]
Answer
Method: Convert to . The scale factor is , so the scale is . The second road represents .
G16 · Know and apply formulae to calculate: area of triangles, parallelograms, trapezia; volume of cuboids and other right prisms (including cylinders)
- Use for a triangle, for a parallelogram and for a trapezium, where each height is perpendicular to the relevant base or parallel sides.
- A right prism has a constant cross-section, so its volume is the area of that cross-section multiplied by the prism length; for a cylinder this gives .
- For example, a trapezium with parallel sides and and perpendicular height has area square units.
- A common error is to use a sloping side as the perpendicular height or to omit the factor of in a triangle or trapezium calculation.
Tier 1 · Easy
1. A trapezium has parallel sides of lengths and and perpendicular height . Work out its area.[2 marks]
Answer
Method: Use . Then .
Tier 2 · Standard
1. A cylinder has radius and height . Work out its volume in terms of .[2 marks]
Answer
Method: The circular cross-section has area . Multiply by the height: .
Tier 3 · Hard
1. A right triangular prism is long. Its triangular cross-section has base and perpendicular height . The volume is . Find .[4 marks]
Answer
Method: The cross-sectional area is . Hence , so . This gives , which factorises to . A length must be positive, so .
G17 · Know circumference of a circle = 2πr = πd and area = πr²; calculate perimeters of 2D shapes incl. circles, areas of circles and composite shapes, surface area and volume of spheres, pyramids, cones
- For a circle, circumference is and area is ; for composite shapes, add included regions or subtract cut-out regions.
- For a pyramid or cone, ; find surface area by adding the base and every exposed triangular face, or use for a cone's curved surface.
- For example, a sphere of radius has surface area and volume , so doubling multiplies these by and respectively.
- A common error is to use the diameter where a formula requires the radius, or to include an internal shared edge or face in a perimeter or surface-area total.
Tier 1 · Easy
1. A circle has diameter . Write its circumference in terms of .[1 mark]
Answer
Method: Use . With , the circumference is .
Tier 2 · Standard
1. A semicircle of diameter is attached to one of the shorter sides of an by rectangle. The shared diameter is inside the shape. Work out the area and perimeter of the composite shape in terms of .[4 marks]
Answer
- Area
- Perimeter
Method: The rectangle area is . The semicircle has radius , so its area is . For the perimeter, include the two sides, the unshared side and the semicircular arc . This gives area and perimeter .
Tier 3 · Hard
1. A solid cone has radius , perpendicular height and slant height . Work out its total surface area, including the circular base, and its volume. Give both answers in terms of .[5 marks]
Answer
- Total surface area
- Volume
Method: The curved surface area is and the base area is , giving in total. The volume is .
G18 · Calculate arc lengths, angles and areas of sectors of circles
- An arc or sector is the same fraction of a circle as its central angle is of .
- Use arc length and sector area , rearranging when the angle or radius is unknown.
- For example, a sector is one quarter of a circle, so its arc length is and its area is .
- A common error is to calculate the full circumference or area without multiplying by , or to include radii when only arc length is requested.
Tier 1 · Easy
1. Work out the arc length of a quarter-circle with radius . Give the answer in terms of .[2 marks]
Answer
Method: A quarter-circle has angle . Its arc length is .
Tier 2 · Standard
1. A sector has radius and arc length . Work out the angle of the sector and its area in terms of .[4 marks]
Answer
- Angle
- Area
Method: Use . Cancelling and solving gives . The sector area is then .
Tier 3 · Hard
1. A shape is an annular sector with angle , outer radius and inner radius . Work out its area and perimeter in terms of .[5 marks]
Answer
- Area
- Perimeter
Method: The area is . The two arcs have total length . The two straight radial edges each have length , so the perimeter is .
G19 · Apply the concepts of congruence and similarity, including the relationships between lengths, areas and volumes in similar figures
- Congruent figures have the same size and shape, while similar figures have equal corresponding angles and corresponding lengths in a constant ratio.
- Match corresponding sides in the same order, calculate one length scale factor, and multiply or divide every corresponding length by that factor.
- At Higher tier only, a length scale factor gives area scale factor and volume scale factor ; for example, length ratio gives area ratio and volume ratio .
- A common error is to compare non-corresponding sides or, at Higher tier, to use the linear scale factor directly for an area or volume.
Tier 1 · Easy
1. Triangle has , and . Triangle has , and . State why the triangles are congruent.[1 mark]
Answer
- They are congruent by SAS.
Method: The triangles have two pairs of equal corresponding sides, and . The equal angle is included between those sides in each triangle, so the triangles are congruent by SAS.
Tier 2 · Standard
1. Two similar shapes have corresponding lengths in the ratio smaller:larger . A side on the smaller shape is . Another side on the larger shape is . Work out the corresponding missing lengths.[3 marks]
Answer
- corresponds to
- corresponds to
Method: The scale factor from smaller to larger is . Therefore . To reverse the enlargement, multiply by , giving .
Tier 3 · Hard
1. Triangle has side lengths , and . Similar triangle has longest side . Work out the other two side lengths of triangle and its perimeter.[4 marks]
Answer
- Other sides and
- Perimeter
Method: The longest sides correspond, so the scale factor is . The other sides are and . The perimeter is .
G20 · Know Pythagoras' theorem a² + b² = c² and the trigonometric ratios sin, cos and tan; apply them to find angles and lengths in right-angled and, where possible, general triangles in 2D and 3D figures
- In a right-angled triangle, with as the hypotenuse, and , , .
- Label the triangle relative to the required angle, choose Pythagoras or the ratio containing the known and unknown sides, and use an inverse trigonometric function when finding an angle.
- At Foundation tier, apply Pythagoras and trigonometry to right-angled triangles in two-dimensional figures, including those found by symmetry in isosceles triangles; at Higher tier only, extend to general (non-right) triangles and identify a right-angled cross-section before applying the same method in three dimensions.
- A common error is to treat a non-right-angled triangle as right-angled, or to use an angle and sides that do not belong to the same right-angled cross-section.
Tier 1 · Easy
1. A right-angled triangle has perpendicular sides and . Work out the hypotenuse.[2 marks]
Answer
Method: By Pythagoras, . Since a length is positive, .
Tier 2 · Standard
1. A straight ladder of length rests against a vertical wall. Its foot is from the wall. Work out the height reached by the ladder and the angle it makes with the ground. Give each answer to decimal place.[4 marks]
Answer
- Height
- Angle
Method: The ladder is the hypotenuse, so the height is . If the ground angle is , then . Hence to decimal place.
Tier 3 · Hard
1. Isosceles triangle has and . Work out the perpendicular height from to and angle . Give the angle to decimal place.[4 marks]
Answer
- Height
Method: The perpendicular from bisects the base, giving a right-angled triangle with hypotenuse and base . Its height is . For , , so to decimal place.
G21 · Know the exact values of sin θ and cos θ for θ = 0°, 30°, 45°, 60° and 90°; know the exact value of tan θ for θ = 0°, 30°, 45° and 60°
- Know the exact sine and cosine values at , , , and , and the exact tangent values at , , and .
- The complete sets are and for ; also , , , .
- For example, the triangle gives , and .
- A common error is to give a decimal approximation when an exact value is required, or to interchange the opposite and adjacent sides for and .
Tier 1 · Easy
1. Work out the exact value of .[1 mark]
Answer
Method: and . Therefore the sum is .
Tier 2 · Standard
1. Work out the exact value of .[3 marks]
Answer
Method: and . Therefore .
Tier 3 · Hard
1. The hypotenuse of a right-angled triangle is and one acute angle is . Work out its exact area.[4 marks]
Answer
Method: The side opposite is . The adjacent side is . Hence the area is .
G22 · Know and apply the sine rule a/sin A = b/sin B = c/sin C, and cosine rule a² = b² + c² - 2bc cos A, to find unknown lengths and angles [Higher only]
- The sine rule pairs each side with its opposite angle, while the cosine rule connects three sides with one angle.
- Use the sine rule when an opposite side-angle pair is known; use the cosine rule for two sides and their included angle or for all three sides.
- When the sine rule gives , check both and against the triangle angle sum.
- A common error is to pair a side with a non-opposite angle or to ignore the second possible angle in an ambiguous sine-rule problem.
Tier 1 · Easy
1. In triangle , side , angle and angle . Work out side .[2 marks]
Answer
Method: By the sine rule, . Hence .
Tier 2 · Standard
1. Two sides of a triangle are and , and the included angle is . Work out the exact length of the third side.[3 marks]
Answer
Method: Using the cosine rule, . Therefore .
Tier 3 · Hard
1. In triangle , , and . Find all possible values of angles and . Give each angle to decimal place.[5 marks]
Answer
- ,
- ,
Method: The sine rule gives . Therefore or . The corresponding third angles are and .
G23 · Know and apply Area = ½ ab sin C to calculate the area, sides or angles of any triangle [Higher only]
- The area of a triangle is , where is the included angle between sides and .
- Substitute the two sides and their included angle to find area, or rearrange before using an inverse sine to find an angle.
- If , both and may give triangles with the same area.
- A common error is to use an angle that is not between the two substituted sides, or to reject an obtuse solution without checking the information given.
Tier 1 · Easy
1. Two sides of a triangle are and , and their included angle is . Work out the area.[2 marks]
Answer
Method: .
Tier 2 · Standard
1. A triangle has area . Two sides have lengths and , and their included angle is . Work out .[3 marks]
Answer
Method: Use . Since , this becomes . Therefore .
Tier 3 · Hard
1. Two sides of a triangle are and . Its area is . Find both possible values of the included angle.[4 marks]
Answer
- or
Method: , so . Between and , this occurs at and .
G24 · Describe translations as 2D vectors
- A translation moves every point through the same horizontal and vertical displacement without changing the shape's size or orientation.
- Describe a translation by the column vector , where positive is right, negative is left, positive is up and negative is down.
- For example, moving units left and units up is the translation vector .
- A common error is to reverse the vector by subtracting the image coordinates from the object coordinates instead of calculating image minus object.
Tier 1 · Easy
1. Point is translated to . Describe the translation as a vector.[2 marks]
Answer
Method: Calculate image minus object in each coordinate: and . The translation vector is .
Tier 2 · Standard
1. Triangle has vertices , and . It is translated by . Write the coordinates of the three image vertices.[3 marks]
Answer
Method: Add to every -coordinate and to every -coordinate. This gives , and .
Tier 3 · Hard
1. A translation maps to . The same translation maps to . Find and describe the translation as a vector.[4 marks]
Answer
Method: From to , the displacement is horizontally and vertically, so the vector is . Therefore the image of has -coordinate . Since , .
G25 · Apply addition and subtraction of vectors, multiplication of vectors by a scalar, and diagrammatic and column representations of vectors; use vectors to construct geometric arguments and proofs
- Vectors have magnitude and direction; they can be represented by directed line segments, column vectors or algebraic symbols such as and .
- Add vectors component by component, subtract to reverse a displacement, and multiply by a scalar to change magnitude and, for a negative scalar, direction.
- For a route through successive points, add vectors in travel order; at Higher tier only, compare two vector routes or show one direction vector is a scalar multiple of another to construct a geometric proof.
- A common error is to subtract vectors in the wrong order or to forget that multiplying by a negative scalar reverses the vector's direction.
Tier 1 · Easy
1. Work out .[1 mark]
Answer
Method: Add corresponding components: and . Therefore the sum is .
Tier 2 · Standard
1. Points and have position vectors and . Point is the midpoint of . Find the position vector of and the vector .[3 marks]
Answer
Method: The midpoint position vector is . Then .
Tier 3 · Hard
1. A walker starts at . The walker makes successive displacements , and . Work out the resultant displacement, the walker's finishing coordinates and the vector that would take the walker directly back to .[4 marks]
Answer
- Resultant
- Finish
- Return vector
Method: First, . Adding all displacements gives . Add this to to get the finish . The return vector is the negative of the resultant, .