Use the value of the trigonometric function to find $\cos ( t + \pi )$ . $\cos t = \frac { 7 } { 8 }$
A) $\cos ( t + \pi ) = \frac { 7 } { 8 }$
B) $\cos ( t + \pi ) = - \frac { 8 } { 7 }$
C) $\cos ( t + \pi ) = \infty$
D) $\cos ( t + \pi ) = \frac { 8 } { 7 }$
E) $\cos ( t + \pi ) = - \frac { 7 } { 8 }$

Question

Use the value of the trigonometric function to find $\cos ( t + \pi )$ .   $\cos t = \frac { 7 } { 8 }$  
A) $\cos ( t + \pi ) = \frac { 7 } { 8 }$
B) $\cos ( t + \pi ) = - \frac { 8 } { 7 }$
C) $\cos ( t + \pi ) = \infty$
D) $\cos ( t + \pi ) = \frac { 8 } { 7 }$
E) $\cos ( t + \pi ) = - \frac { 7 } { 8 }$

Quizplus · Accepted Answer

The cosine function has a period of $2\pi$, meaning $\cos(t + \pi) = -\cos(t)$. Given $\cos(t) = \frac{7}{8}$, $\cos(t + \pi) = -\frac{7}{8}$.

Use the Value of the Trigonometric Function to Find cos⁡(t+π)\cos ( t + \pi )cos(t+π)

Use the Value of the Trigonometric Function to Find $\cos ( t + \pi )$