Definition:Acute Angle
From ProofWiki
Definition
An acute angle is an angle which has a measure between that of a right angle and that of a zero angle.
As Euclid defined it:
- An acute angle is an angle less than a right angle.
(The Elements: Book I: Definition $12$)
The measurement $\theta$ of an acute angle is such that $0^\circ < \theta < 90^\circ$ or $0$ rad $< \theta < \dfrac \pi 2$ rad.
