AUTHOR

EVERYTHING YOU NEED TO KNOW TO GET A GRADE C

GEOMETRY & MEASURES

(FOUNDATION)

Rhombus

Trapezium

Rectangle

Rhombus

Rhombus

Parallelogram Rhombus

Trapezium or Right-angle Trapezium

110°

Base angles in a kite are equal

Opposite angles in a rhombus are equal

250°

Angles around a point sum to 360°

Angles in a kite sum to 360°

30

Kite

Trapezium

Replace a with 3 and b with 5.2 P = 2 x 3 + 2 x 5.2P = 6 + 10.4

16.4

Total areas of both shapes are equal to one as shown.

Equilateral triangle

Rhombus

2 (Fits on top of itself twice through a full turn)

9cm

5cm 5cm

5cm

3cm 3cm Can choose either as your answer

Any two of rectangle, parallelogram, kite or arrowhead

The 3cm and 5cm rods would not meet when joined with the 9cm rod.

In an isosceles triangle, the base angles are the same

Angles in a triangle sum to

180°

80 20

50 50

Each angle is 60° in an equilateral triangle

120° because angles on a straight line add to 180°30° because angles in a right angle add to 90°

Base angles are both 30° so ABD is an isosceles triangle

Isosceles TriangleAngles in a triangle

add to 180°

180° - 34° = 146° 146° ÷ 2 = 73°

73

73°

73°

107°

107° because angles on a straight line add up to 180°

y = 180° - 107° - 38° = 35°

35

35°

No, because 38° is not equal to 35°. Therefore, it is not an isosceles triangle

180° - 126° = 54° 54° ÷ 2 = 27°

27° 27° 153°

153° because angles on a straight line add up to 180°

Angles in a triangle add to 180°

27 153

Base angles are the same in an isosceles triangle

80°

Angles in a triangle add to 180°180° - 80° - 80° = 20°

20

Means work out angle A in triangle ABC

Means work out angle R in triangle PQR

Base angles are the same in an isosceles triangle

70°

Angles in a triangle add to 180°180° - 70° - 70° = 40°

40°

A right angle is 90°90° - 40° = 50°

50°

Both base angles are equal180° - 50° = 130° 130° ÷ 2 = 65°

65°65°

65

180° - 48° = 132° 132° ÷ 2 = 66°

66° 66°

Angles on a straight line add to 180°180° - 66° = 114°

114°

114

A quadrilateral is made up of two triangles Angles is a triangle add up to 180°

180°

180° 180° + 180° = 360°

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(because the exterior angles add up to 360°)

Exterior angle = 72°

72°

Two exterior angles joined

togetherAs worked out in part (a)

72°

144

All the angles and sides are the same in a regular pentagon

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Exterior angle

Exterior angle

Exterior angle

Exterior angle

Exterior angle

= 72°

72°

72°

72°

72°

72°

Interior angle

Angles on a straight line add up 180° Interior angle = 180° - 72° = 108°

108°

Base angles in a isosceles triangle are the same 180° - 108° = 72°

36°

36°

36

LEARN OFF BY HEARTInterior angle

Exterior angle

Angles on a straight line add up 180°

Exterior angle = 180° - 162° = 18°

= 20 20

Decagon Pentagon

Interior angle

Sum of interior angles of an decagon = (10 – 2) x 180°

Sum of interior angles = (number of sides – 2) x 180°

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= 8 x 180° = 1440°

= 144°

144°Interior angle

Sum of interior angles of a pentagon = (5 – 2) x 180° = 3 x 180° = 540°

= 108°

108°

Angles around a point add up to 360°

360° - 144° - 108° = 108°

108°

Base angles in a isosceles triangle are the same

180° - 108° = 72° 72° ÷ 2 = 36°

36°36°

144°

144° + 36° = 180° (Angles on a straight line add up to 180°) Therefore, ABC lie on a straight line

Hexagon

Square

Square

Sum of interior angles = (number of sides – 2) x 180°

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Sum of interior angles of an hexagon = (6 – 2) x 180° = 4 x 180° = 720°

= 120°

Interior angle120°

Angles around a point add up to 360°

360° - 120° - 90° - 90° = 60°

60°

Base angles are the same

180° - 60° = 120° 120° ÷ 2 = 60°

60°60°

Therefore, as all angles are 60° AHJ is equilateral

Sum of interior angles = (number of sides – 2) x 180°

LEARN OFF BY HEARTSum of interior angles of an octagon = (8 – 2) x 180° = 6 x 180° = 1080°

= 135°

135

= 135° As worked out in part (a)

135°

135°135°

135° 135°135°

135°135°

Angles around a point add up to 360°

360° - 135° - 135° = 90°

Therefore, as all angles are 90° PQRS is a square