How it works
Put the centre on the corner and the baseline on one ray.
Start at zero on the baseline. Read the mark where the second ray crosses.
An angle under 90 is acute. 90 is right. More than 90 and less than 180 is obtuse.
Worked examples
A right angle
- An angle measures 90 degrees.
- That is exactly a square corner.
- It is a right angle.
Read the scale
- The baseline is on the left and the other ray crosses 150.
- Read from the zero on the baseline.
- The angle is 150 degrees. It is obtuse.
An acute angle
- An angle measures 45 degrees.
- It is less than 90.
- It is an acute angle.
A taste of the worksheet
These are the first problems of set A. The printable sheet has many more, with an answer key.
- The baseline lies along zero. How many degrees is the angle? ___
- Is the angle acute, right or obtuse?
- Read the protractor. How many degrees is this angle? ___
- Count the small marks. How many degrees is this angle? ___
- Use the protractor. What kind of angle is this?