91Ó°ÊÓ

evaluate the trigonometric function at the quadrantal angle, or state that the expression is undefined. $$ \cot \frac{\pi}{2} $$

Find the exact value of each expression. $$ \tan ^{-1} 0 $$

Determine the amplitude and period of each function. Then graph one period of the function. $$y=-\sin \frac{2}{3} x$$

Use the given triangles to evaluate each expression. If necessary, express the value without a square root in the denominator by rationalizing the denominator. $$ \sin \frac{\pi}{4}-\cos \frac{\pi}{4} $$

Find the exact value of each expression. $$ \tan ^{-1}(-1) $$

In Exercises \(13-20,\) convert each angle in degrees to radians. Express your answer as a multiple of \(\pi\). $$ 150^{\circ} $$

evaluate the trigonometric function at the quadrantal angle, or state that the expression is undefined. $$ \tan \frac{\pi}{2} $$

In Exercises \(5-18,\) the unit circle has been divided into twelve equal arcs, corresponding to t-values of $$ 0, \frac{\pi}{6}, \frac{\pi}{3}, \frac{\pi}{2}, \frac{2 \pi}{3}, \frac{5 \pi}{6}, \pi, \frac{7 \pi}{6}, \frac{4 \pi}{3}, \frac{3 \pi}{2}, \frac{5 \pi}{3}, \frac{11 \pi}{6}, \text { and } 2 \pi $$ Use the \((x, y)\) coordinates in the figure to find the value of each trigonometric function at the indicated real number, t, or state that the expression is undefined. $$ \cos \frac{3 \pi}{2} $$

Determine the amplitude and period of each function. Then graph one period of the function. $$y=-\sin \frac{4}{5} x$$

\(\theta\) is an acute angle and sin u and cos u are given. Use identities to find tan \(\theta\), csc \(\theta\), sec \(\theta\), and cot \(\theta\). Where necessary, rationalize denominators. $$ \sin \theta=\frac{8}{17}, \quad \cos \theta=\frac{15}{17} $$