The inclination of one line to another. One complete revolution equals 360° (degrees) or 2π radians.
The five types of angles are zero, acute, right, obtuse, and straight.
An angle starts at the initial side and ends at the terminal side
if this is anti-clockwise then the angle is positive
if this is clockwise then the angle is negative
See also: Acute Angle, Angle Bisector, Corresponding Angles, Coterminal Angles, Initial Side, Obtuse Angle, Plane Angle, Protractor, Radian, Reflex Angle, Right Angle, Same Side Exterior Angles, Same Side Interior Angles, Straight Angle, Supplementary Angles, Terminal Side, Vertical Angles, Zero Angle.