Angles and symmetry
Lesson 5 of 10
Measuring angles
Objective. Use a protractor to measure and draw angles accurately.
The key idea
Place the centre of the protractor on the vertex and one arm on the zero line, then read the scale that starts at zero on that arm.
Worked example
An angle looks less than a right angle and the protractor reads 60 or 120. Which is it?
- 1Less than a right angle means less than 90°.
- 2So the correct reading is 60°.
Answer: 60°
Practice
Each question comes with a picture and a listen button. Try it first, then reveal the answer.
Common mistake. Reading the wrong protractor scale and getting the supplement of the angle.
Your progress
Tick each step as you finish it — Continue brings you back here.
0 of 5 steps complete