What type of angle measures exactly 180 degrees?

A straight angle measures exactly 180 degrees. This type of angle is formed when two rays point in opposite directions, creating a straight line. In geometric terms, when you have an angle at this measurement, it splits the line into two equal halves, demonstrating that the sum of the angles on either side of the straight angle is precisely half of a full rotation (360 degrees).

This characteristic differentiates it from other angles. For instance, a right angle measures 90 degrees, which is a quarter of a full rotation and indicates a perpendicular intersection of lines. An acute angle measures less than 90 degrees, representing a sharp smaller angle, while an obtuse angle measures more than 90 degrees, representing a wider angle but still less than 180 degrees. Thus, the unique measurement of 180 degrees specifically defines a straight angle.