Measurements of Common Angles/Reflex Angle

Theorem
A reflex angle measures $\theta$, where:
 * $180^\circ < \theta < 360^\circ$

or:
 * $\pi < \theta < 2 \pi$

Proof
A reflex angle is defined to be an angle whose measure is between that of a straight angle and a full angle.

A straight angle measures $180^\circ$ or $\pi$ and a full angle measures $360^\circ$ or $2 \pi$.

Hence the result.