Evaluate the trigonometric function using its period as an aid. $\cos \frac { 5 \pi } { 3 }$
A) $\cos \frac { 5 \pi } { 3 } = \infty$
B) $\cos \frac { 5 \pi } { 3 } = - \frac { 1 } { 2 }$
C) $\cos \frac { 5 \pi } { 3 } = 2$
D) $\cos \frac { 5 \pi } { 3 } = - 2$
E) $\cos \frac { 5 \pi } { 3 } = \frac { 1 } { 2 }$

Question

Evaluate the trigonometric function using its period as an aid.​ $\cos \frac { 5 \pi } { 3 }$ ​
A) $\cos \frac { 5 \pi } { 3 } = \infty$
B) $\cos \frac { 5 \pi } { 3 } = - \frac { 1 } { 2 }$
C) $\cos \frac { 5 \pi } { 3 } = 2$
D) $\cos \frac { 5 \pi } { 3 } = - 2$
E) $\cos \frac { 5 \pi } { 3 } = \frac { 1 } { 2 }$

Quizplus · Accepted Answer

The cosine function has a period of $2\pi$, so $\cos \frac{5\pi}{3}$ is equivalent to $\cos(-\frac{\pi}{3})$, which equals $\frac{1}{2}$.

Evaluate the Trigonometric Function Using Its Period as an Aid cos⁡5π3\cos \frac { 5 \pi } { 3 }cos35π​

Evaluate the Trigonometric Function Using Its Period as an Aid $\cos \frac { 5 \pi } { 3 }$