Angle: Formed by two rays (sides) from a common point (vertex).
Degree: 1/360 of a full rotation. π radians = 180°.
Radian: Angle subtended by arc equal in length to the radius.
Types of angles: acute (<90°), right (90°), obtuse (90°–180°), straight (180°), reflex (>180°).
Angle: 45°
Radians: 0.79