Do Now The terminal side of angle θ in standard position passes through the point (12, 16). Find the value of the six trigonometric functions of angle θ.

Section 1.3 Trigonometric Functions Objective: SWBAT use trigonometric functions with quadrantal angles.

Quadrantal Angles Quadrantal Angle: An angle whose terminal side is on an axis. Think about x or y equaling 0. What would happen to the value of r in your trigonometric functions?

FINDING FUNCTION VALUES OF QUADRANTAL ANGLES Example 1 FINDING FUNCTION VALUES OF QUADRANTAL ANGLES Find the values of the six trigonometric functions for an angle of 90°. The terminal side passes through (0, 1). So x = 0, y = 1, and r = 1. undefined undefined

FINDING FUNCTION VALUES OF QUADRANTAL ANGLES Example 2 FINDING FUNCTION VALUES OF QUADRANTAL ANGLES Find the values of the six trigonometric functions for an angle θ in standard position with terminal side through (–3, 0). x = –3, y = 0, and r = 3. undefined undefined

Undefined Function Values If the terminal side of a quadrantal angle lies along the y-axis, then the tangent and secant functions are undefined. If the terminal side of a quadrantal angle lies along the x-axis, then the cotangent and cosecant functions are undefined.

Commonly Used Function Values  sin  cos  tan  cot  sec  csc  0 1 undefined 1 undefined 1 undefined 90 undefined 1 180 1 undefined 270 undefined 1 360

Using a Calculator A calculator in degree mode returns the correct values for sin 90° and cos 90°. The second screen shows an ERROR message for tan 90° because 90° is not in the domain of the tangent function.

Caution One of the most common errors involving calculators in trigonometry occurs when the calculator is set for radian measure, rather than degree measure.

Homework: Page 25 #’s 34-42 (evens)