Definition:Obtuse Angle

Definition
An obtuse angle is an angle which has a measurement between those of a right angle and a straight angle.



Note that Euclid did not consider the concept of reflex angles.

The measurement $\theta$ of an obtuse angle is such that $90^\circ < \theta < 180^\circ$ or $\dfrac \pi 2$ rad $< \theta < \pi$ rad.