What is the measure of a straight angle?

• A. 90 degrees
• B. 180 degrees
• C. 360 degrees
• D. 45 degrees

Answer: (B)

A straight angle is defined as an angle that measures exactly 180 degrees. This measurement represents the scenario where two rays or lines extend in opposite directions from a common point, effectively forming a straight line.

To visualize this, imagine a line segment extended in one direction. If you were to rotate one end of the line segment until it overlaps with the other end, the rotation will create a half-turn, which corresponds to 180 degrees.

Understanding that a straight angle creates a linear path is essential, and differentiating it from other angles is also helpful; for example, a right angle measures 90 degrees, which is an angle that represents one quarter of a full turn, while a full angle measures 360 degrees, signifying a complete rotation. The 45-degree angle represents an even smaller fraction of a full turn than a right angle. Hence, the measure of a straight angle is definitively 180 degrees.