How many degrees are in a right angle?

A right angle is defined as the angle formed when two lines are perpendicular to each other. This angle measures exactly 90 degrees. It represents a quarter of a complete turn, which is why it is a fundamental element in geometry. The significance of 90 degrees is evident in various applications, such as in constructing squares and rectangles, where right angles are essential for the correct formation of these shapes.

The other options represent angles that are commonly known but do not describe a right angle. For instance, 45 degrees is the measure of an acute angle, which is less than a right angle. An angle measuring 180 degrees is a straight angle, indicating a straight line rather than a perpendicular relationship. Finally, 360 degrees represents a full rotation, where the lines come back to their starting position, far exceeding the measure of a right angle. Therefore, the only option that correctly identifies the measure of a right angle is 90 degrees.