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Grade 8 · Geometry of Straight Lines
Angle Relationships: Straight, Intersecting & Perpendicular Lines
MEMORANDUM
Name:
Class:
Date:
Mark
/ 19
Answer all questions. Show all your working — marks are awarded for method as well as the final answer. Teacher copy: accept any correct equivalent method.
- 1Two angles on a straight line are (3x + 5)° and (x + 15)°. Determine the value of x, and hence the size of each angle.(4)Angles on a straight line add up to 180° (1)
4x + 20 = 180 (1)
x = 40 (1)
The angles are 125° and 55° (1)✓✓✓✓ (4) - 2Two vertically opposite angles are (4x + 10)° and (2x + 50)°. Determine the value of x, and hence the size of each angle.(4)Vertically opposite angles are equal (1)
2x = 40 (1)
x = 20 (1)
The angles are 90° and 90° (1)✓✓✓✓ (4) - 3Angles of 70° and x lie on a straight line. Find x.(1)180° − 70° = 110°✓ (1)
- 4Angles of 95° and y lie on a straight line. Find y.(1)180° − 95° = 85°✓ (1)
- 5Angles of 140°, 90° and p meet at a point. Find p.(2)360° − 230° = 130°✓✓ (2)
- 6Two lines cross forming an angle of 48°. What is its vertically opposite angle?(1)48° (vertically opposite angles are equal)✓ (1)
- 7Two lines cross forming an angle of 48°. What is the neighbouring angle?(2)180° − 48° = 132°✓✓ (2)
- 8A right angle is split into 28° and k. Find k.(1)90° − 28° = 62°✓ (1)
- 9What does AB ⊥ CD mean?(1)AB is perpendicular to CD — they meet at 90°.✓ (1)
- 10Angles 3x and 2x lie on a straight line. Find x.(2)3x + 2x = 180 → 5x = 180 → x = 36°✓✓ (2)
TOTAL: 19 marks