Find the exact value. Do not use a calculator.
-$\sec \frac { 13 \pi } { 4 }$
A) $- \frac { 2 \sqrt { 3 } } { 3 }$
B) $- 2$
C) $- \sqrt { 2 }$
D) $\frac { \sqrt { 2 } } { 2 }$

Question

Quizplus · Accepted Answer

$\sec \frac { 13 \pi } { 4 } = \sec (\pi + \frac { 5 \pi } { 4 }) = \sec (\frac { 5 \pi } { 4 })$. Since $\sec \theta = \frac{1}{\cos \theta}$, and $\cos \frac { 5 \pi } { 4 } = -\frac{\sqrt{2}}{2}$, then $\sec \frac { 5 \pi } { 4 } = -\sqrt{2}$.

Find the Exact Value sec⁡13π4\sec \frac { 13 \pi } { 4 }sec413π​

Find the Exact Value $\sec \frac { 13 \pi } { 4 }$