Angles on a line and round a point · Year 5
In Year 5 you learn: angles on a straight line add to 180° and angles round a point add to 360°.
Angles that sit together on a straight line make a half turn, and angles that meet at a point make a full turn. When two straight lines cross, the opposite angles are equal. These three facts solve a huge number of angle problems.
Key facts
- Angles on a straight line add up to 180°.
- Angles round a point add up to 360°.
- Neighbouring angles where two lines cross add up to 180°.
Worked examples
Example 1
Find the angle x.
Answer: x = 124°
Example 2
Angles of x, 2x and 120° meet at a point. Find x.
Answer: x = 80°