This document defines and describes different types of angles: a right angle is 90 degrees; an acute angle is less than 90 degrees; an obtuse angle is greater than 90 degrees but less than 180 degrees; a straight angle is 180 degrees; and a reflex angle is greater than 180 degrees but less than 360 degrees. It then asks the reader to identify what type of angle is being described from options for five different angles.