Graph y 1 3 tan x for x . y

Math 113 Sec 5.1 Page 1 of 4 Section 5.1 Angle Measure An angle is formed by rotating a ray around its endpoint. • Initial side – original position of the ray • Terminal side – ending position of the ray • Vertex – endpoint of the ray Angle in standard position – vertex at origin of a rectangular coordinate system; initial side is positive x-axis. Positive angle – rotated counterclockwise Negative angle – rotated clockwise Greek letters commonly used to name angles: (alpha), (beta), (theta), (gamma), (phi) Degree Measure On a rectangular coordinate system (standard position): Acute angle: 0° < < 90° Obtuse angle: 90° < < 180° Right angle: measures exactly 90°