What is a straight angle?

A straight angle is an angle that measures exactly 180 degrees. Here's what characterizes it:

  • Appearance: It forms a straight line. Imagine a perfectly flat, extended line; that's a straight angle.

  • Measure: Its most defining feature is its 180° measure.

  • Relationship to other angles: It's twice the size of a right angle (90°). It can be thought of as the sum of two right angles.

  • Use in Geometry: Straight angles are fundamental in geometry. They're used to define supplementary angles (two angles that add up to 180°) and are often encountered when working with lines and polygons.

  • Not a "proper" angle: Although technically an angle, it's sometimes excluded from certain discussions because it's a degenerate case – it's essentially a line rather than a distinct angle in the same way an acute or obtuse angle is.