Missing Angles - Year 6 Maths Worksheet | Teach Starter - Free Printable

Let’s solve each problem one by one. We’ll use the fact that:

- A right angle = 90°
- A straight line (straight angle) = 180°
- If angles are next to each other and form a bigger angle, we can add or subtract them to find missing parts.

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Problem 1:
We see a right angle (90°), split into two parts: one is 20°, the other is x.
So:
x + 20° = 90°
→ x = 90° - 20° = 70°

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Problem 2:
This is a straight line (180°). One part is 140°, the other is x.
So:
x + 140° = 180°
→ x = 180° - 140° = 40°

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Problem 3:
Right angle again (90°), split into three parts: x, 30°, and 30°.
So:
x + 30° + 30° = 90°
→ x + 60° = 90°
→ x = 90° - 60° = 30°

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Problem 4:
Right angle (90°), split into three parts: x, 15°, and 10°.
So:
x + 15° + 10° = 90°
→ x + 25° = 90°
→ x = 90° - 25° = 65°

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Problem 5:
Right angle (90°), split into three parts: 25°, x, and 20°.
So:
25° + x + 20° = 90°
→ x + 45° = 90°
→ x = 90° - 45° = 45°

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Problem 6:
Straight line (180°), split into three parts: x, 40°, and 60°.
So:
x + 40° + 60° = 180°
→ x + 100° = 180°
→ x = 180° - 100° = 80°

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Problem 7:
Right angle (90°), split into three parts: 40°, x, and 30°.
So:
40° + x + 30° = 90°
→ x + 70° = 90°
→ x = 90° - 70° = 20°

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Problem 8:
Straight line (180°), split into three parts: 20°, x, and 20°.
So:
20° + x + 20° = 180°
→ x + 40° = 180°
→ x = 180° - 40° = 140°

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Problem 9:
Straight line (180°), split into three parts: x, 45°, and 20°.
So:
x + 45° + 20° = 180°
→ x + 65° = 180°
→ x = 180° - 65° = 115°

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Final Answer:
1) 70°
2) 40°
3) 30°
4) 65°
5) 45°
6) 80°
7) 20°
8) 140°
9) 115°