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Secondary 1 Mathematics · Angles and parallel lines

Name: ______________________

Date: ____________

1. Angles that are between two parallel lines and on opposite sides of the transversal (forming a Z shape) are called:
- ☐ (a) Corresponding angles
- ☐ (b) Alternate angles
- ☐ (c) Co-interior angles
- ☐ (d) Vertically opposite angles
2. When the lines are parallel, co-interior angles:
- ☐ (a) add to 90°
- ☐ (b) add to 180°
- ☐ (c) add to 360°
- ☐ (d) are equal
3. One of a pair of corresponding angles on parallel lines is 48°. What is the other?
- ☐ (a) 42°
- ☐ (b) 48°
- ☐ (c) 132°
- ☐ (d) 312°
4. Two co-interior angles on parallel lines are 75° and y°. What is y?
- ☐ (a) 75
- ☐ (b) 105
- ☐ (c) 15
- ☐ (d) 285
5. One of a pair of alternate angles on parallel lines is 117°. What is the size of the other angle, in degrees?
6. One of a pair of co-interior angles on parallel lines is 64°. What is the size of the other angle, in degrees?
7. A pair of corresponding angles on parallel lines are (3x)° and 81°. Find x.
8. A transversal crosses two lines. A pair of co-interior angles measure 95° and 85°. Are the two lines parallel? Answer yes or no.

Answer sheet

1. Alternate angles — Alternate angles form a Z shape and are equal when the lines are parallel.
2. add to 180° — Co-interior angles (C shape) are supplementary, so they add to 180°.
3. 48° — Corresponding angles on parallel lines are equal, so the other angle is 48°.
4. 105 — Co-interior angles add to 180°: y = 180 − 75 = 105.
5. 117° — Alternate angles on parallel lines are equal, so it is also 117°.
6. 116° — Co-interior angles add to 180°: 180 − 64 = 116°.
7. x = 27 — Corresponding angles are equal: 3x = 81, so x = 81 ÷ 3 = 27.
8. Yes — 95° + 85° = 180°. Co-interior angles that add to 180° show that the lines are parallel.