# Measurements of Common Angles/Acute Angle

## Theorem

An acute angle measures $\theta$, where:

$0 \degrees < \theta < 90 \degrees$

or:

$0 < \theta < \dfrac \pi 2$

## Proof

An acute angle is defined to be an angle whose measure is between that of a zero angle and a right angle.

A zero angle measures $0$ by definition, and a right angle measures $90 \degrees$ or $\dfrac \pi 2$.

Hence the result.

$\blacksquare$