Definition:Acute Angle

From ProofWiki
Jump to: navigation, search

Definition

An acute angle is an angle which has a measure between that of a right angle and that of a zero angle.


In the words of Euclid:

An acute angle is an angle less than a right angle.

(The Elements: Book $\text{I}$: Definition $12$)


Measurement of Acute Angle

An acute angle measures $\theta$, where:

$0^\circ < \theta < 90^\circ$

or:

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


Sources