Different types of angles

An acute angle is less than 90^\circ.

Acute angle diagram

A right angle is exactly 90^\circ.

Right angle diagram

An obtuse angle is between 90^\circ and 180^\circ.

Obtuse angle diagram

A straight angle or an angle on a straight line is exactly 180^\circ.

Straight angle (180°) diagram

A reflex angle is between 180^\circ and 360^\circ.

Reflex angle diagram

A full turn or complete revolution is exactly 360^\circ.

Full turn (360°) diagram