Radians- A unit of angle, equal to an angle at the center of a circle whose arc is equal in length to the radius- A straight line from the center to the circumference of a circle or sphere.
Degrees- A unit of measurement of angles, one three-hundred-and-sixtieth of the circumference of a circle.
Initial Side- A stationary straight line that contains a point about which another straight line is rotated to form an angle
Terminal Side- An angle is in standard position if its vertex is located at the origin and one ray is on the positive x-axis.
Coterminal Angle- angles in standard position (angles with the initial side on the positive x-axis) that have a common terminal side.
Reference Angle- is the smallest angle between the terminal side and the x-axis.
Unit Circle- is a circle with a radius of one
Trig Ratios (Sine, Cosine, Tangent, Secant, Cosecant, Cotangent)- they areratios of two sides of a right triangle and a related angle.