Angles are measured in units called degrees. The degree of an angle is a number from 0 to 360 that tells you how large the angle is. It represents how much "turn" or incline the angle has. Degrees are indicated by writing a number followed by the symbol "°" to the right of the number. For example, 45° means 45 degrees. To write that the measure of angle A is 45 degrees, you would write m\(\mathsf{ \angle }\)A = 45°.

Here is what a 45° angle looks like:

To measure the degrees of an angle, you'll need a special tool called a protractor. You can verify that the angle above is 45° by laying the protractor on top of the angle, as shown below. (Note: The initial side, or base, of the angle is placed along the straightedge of the protractor.