91Ó°ÊÓ

Exer. 51-60: Show that the equation is not an identity. (Hint: Find one number for which the equation is false.) $$ \cos (-t)=-\cos t $$

Exer. 39-62: Find the solutions of the equation that are in the interval \([0,2 \pi\) ). $$ \cot \alpha+\tan \alpha=\csc \alpha \sec \alpha $$

Exer. 57-62: Use an addition or subtraction formula to find the solutions of the equation that are in the interval \([0, \pi\) ). $$ \sin 4 t \cos t=\sin t \cos 4 t $$

Exer. 53-64: Use inverse trigonometric functions to find the solutions of the equation that are in the given interval, and approximate the solutions to four decimal places. \(3 \tan ^{4} \theta-19 \tan ^{2} \theta+2=0 ; \quad\left(-\frac{\pi}{2}, \frac{\pi}{2}\right)\)

Exer. 39-62: Find the solutions of the equation that are in the interval \([0,2 \pi\) ). $$ \sin x+\cos x \cot x=\csc x $$

Exer. 57-62: Use an addition or subtraction formula to find the solutions of the equation that are in the interval \([0, \pi\) ). $$ \cos 5 t \cos 3 t=\frac{1}{2}+\sin (-5 t) \sin 3 t $$

Exer. 53-64: Use inverse trigonometric functions to find the solutions of the equation that are in the given interval, and approximate the solutions to four decimal places. \(6 \sin ^{3} \theta+18 \sin ^{2} \theta-5 \sin \theta-15=0 ; \quad\left(-\frac{\pi}{2}, \frac{\pi}{2}\right)\)

Exer. 57-62: Use an addition or subtraction formula to find the solutions of the equation that are in the interval \([0, \pi\) ). $$ \cos 5 t \cos 2 t=-\sin 5 t \sin 2 t $$

Exer. 39-62: Find the solutions of the equation that are in the interval \([0,2 \pi\) ). $$ 2 \sin ^{3} x+\sin ^{2} x-2 \sin x-1=0 $$

Exer. 51-60: Show that the equation is not an identity. (Hint: Find one number for which the equation is false.) $$ \cos (\sec t)=1 $$