The measure of the angle, which is equal to its complement, is:

The correct answer is: 45°

If the sum of the measures of two angles is 90 degrees , the angles are called complementary angles.

Here, complement of the angle x° and x° are added to get 90 degrees.

Complementary angle = 90° − given angle

x° + x° = 90° ⇒ x° = 45°.

The measure of the complement of the angle 45° is 45°. 

Therefore, required angle is 45°.