Degree and Radian Measure

Angle is determined by two rays, the terminal and initial ray. Angle is represented by a Greek letter theta ϴ. It can be measured using different units, such as revolutions, rotations, degrees, radians, and gradians.

Angle of rotation is defined by rotating a ray about its endpoint, making a vertex. The starting point is the Initial side and the result is called the terminal side.

Angle measures without units are considered in radians. Angles in degrees must show the symbol. Obtuse angles are greater than 90 degrees and acute are less. A positive angle rotates counter clockwise and a angle to be negative, the rotation is clockwise

An angle in standard position must have the vertex as the origin and initial side on the positive x-axis. The measure between the terminal and x-axis is called the reference angle.

Radian measure is another way to measure angles.

Arc length of a circle is found with the  formula a=ϴr. R is the radius and theta is the angle in radians. To
convert to radians you multiply the degrees measure by /180. And to convert degrees to radians you multiply by 180.