How many degrees are there in a straight angle?

A straight angle measures exactly 180 degrees. This is defined by the fact that a straight angle forms a straight line, where the two rays that create the angle point in opposite directions. The total rotation around a point is 360 degrees, with a half-rotation, which forms a straight line, being 180 degrees.

The definition of angles categorizes them based on their measures: acute angles measure less than 90 degrees, right angles measure exactly 90 degrees, obtuse angles measure more than 90 degrees but less than 180 degrees, and straight angles measure exactly 180 degrees. Thus, recognizing that a straight angle is essentially the largest angle defined before it reaches a complete rotation emphasizes its exact measurement of 180 degrees.