Evaluate the trigonometric function using its period as an aid. $$\cos \frac { 9 \pi } { 4 }$$
A)$\cos \frac { 9 \pi } { 4 } = - \frac { \sqrt { 2 } } { 2 }$
B) $\cos \frac { 9 \pi } { 4 } = - \sqrt { 2 }$
C) $\cos \frac { 9 \pi } { 4 } = \sqrt { 2 }$
D) $\cos \frac { 9 \pi } { 4 } = \frac { \sqrt { 2 } } { 2 }$
E) $\cos \frac { 9 \pi } { 4 } = \infty$

Question

Evaluate the trigonometric function using its period as an aid. $$\cos \frac { 9 \pi } { 4 }$$ 
A)$\cos \frac { 9 \pi } { 4 } = - \frac { \sqrt { 2 } } { 2 }$
B) $\cos \frac { 9 \pi } { 4 } = - \sqrt { 2 }$
C) $\cos \frac { 9 \pi } { 4 } = \sqrt { 2 }$
D) $\cos \frac { 9 \pi } { 4 } = \frac { \sqrt { 2 } } { 2 }$
E) $\cos \frac { 9 \pi } { 4 } = \infty$

Quizplus · Accepted Answer

The Answer of Evaluate the trigonometric function using its period as an aid. $$\cos \frac { 9 \pi } { 4 }$$ 
A)$\cos \frac { 9 \pi } { 4 } = - \frac { \sqrt { 2 } } { 2 }$
B) $\cos \frac { 9 \pi } { 4 } = - \sqrt { 2 }$
C) $\cos \frac { 9 \pi } { 4 } = \sqrt { 2 }$
D) $\cos \frac { 9 \pi } { 4 } = \frac { \sqrt { 2 } } { 2 }$
E) $\cos \frac { 9 \pi } { 4 } = \infty$

Evaluate the Trigonometric Function Using Its Period as an Aid cos⁡9π4\cos \frac { 9 \pi } { 4 }cos49π​

Evaluate the Trigonometric Function Using Its Period as an Aid $\cos \frac { 9 \pi } { 4 }$