8th Grade Angles Worksheet — Level 3 — Practice Set 2 — Answers
Answer sheet with worked solutions for the 8th Grade angles worksheet.
Success TutoringWorksheetsAnswer sheet8th Grade · Mathematics · Angles8th Grade Angles Worksheet — Level 3 — Practice Set 2 — Answers
State the angle rule you use.
1.Three angles meet at a point: 149°, 139° and x°. Find x.
Answer: x = 72
- Angles at a point add to 360°
- x = 360 − 149 − 139 = 72
2.Two angles of a triangle are 49° and 80°. Find the third angle.
Answer: 51°
- Angles in a triangle add to 180°
- 180 − 49 − 80 = 51
3.Two angles of a triangle are 53° and 94°. Find the third angle.
Answer: 33°
- Angles in a triangle add to 180°
- 180 − 53 − 94 = 33
4.Two angles of a triangle are 30° and 111°. Find the third angle.
Answer: 39°
- Angles in a triangle add to 180°
- 180 − 30 − 111 = 39
5.Two angles on a straight line are 33° and x°. Find x.
Answer: x = 147
- Angles on a straight line add to 180°
- x = 180 − 33 = 147
6.An isosceles triangle has an apex angle of 29°. Find each base angle.
Answer: 75.5°
- Base angles are equal: (180 − 29) ÷ 2
- = 151 ÷ 2 = 75.5
7.Three angles meet at a point: 120°, 155° and x°. Find x.
Answer: x = 85
- Angles at a point add to 360°
- x = 360 − 120 − 155 = 85
8.Two angles on a straight line are 127° and x°. Find x.
Answer: x = 53
- Angles on a straight line add to 180°
- x = 180 − 127 = 53
9.Two angles of a triangle are 23° and 40°. Find the third angle.
Answer: 117°
- Angles in a triangle add to 180°
- 180 − 23 − 40 = 117
10.An isosceles triangle has an apex angle of 69°. Find each base angle.
Answer: 55.5°
- Base angles are equal: (180 − 69) ÷ 2
- = 111 ÷ 2 = 55.5
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.
Great work. Here's what to try next: