This document provides an introduction to radian measure and reciprocal trigonometric functions. It defines a radian as the central angle that intercepts an arc of a circle equal in length to the radius. Examples are provided for converting between degrees and radians. The six trigonometric functions (sine, cosine, tangent, cosecant, secant, and cotangent) are defined, with the last three being the reciprocals of the first three. Examples are given of finding all six trig functions given values of tangent or cosecant.