Basic, GCSE(F),

Angles are measured using a **protractor**. A protractor measures in **degrees**. A protractor is normally a semi-circle (as found in geometry sets) or a complete circle.

There are four basic steps to measuring an angle accurately using a protractor.

1. Place the centre of the protractor (the middle of the bottom line, normally shown with a circle) *exactly* on the point of the angle being measured:

2. Make sure that the base line of the protractor is *exactly* on top of one of the lines of the angle:

3. Check if the inner scale (of numbers) or the outer scale is being used by determining which scale is at 0º on the line:

4. Read the angle measurement from the correct (inner or outer) scale:

In this instance, the angle being measured is 42º

1. What is the size of the angle being measured below?

Answer: 55º

The zero is on the inner scale. Reading from the zero, read an angle of 55º.

2. What is the size of the angle being measured, below?

Answer: 132º

The zero is on the outer scale. Read round the outer scale to 132º.

Our iOS app has over 1,000 questions to help you practice this and many other topics.

Available to download free on the App Store.

Available to download free on the App Store.