Find a cofunction with the same value as the given expression.
-$\cos \frac { \pi } { 8 }$
A) $\sin \frac { 3 \pi } { 8 }$
B) $\cos \frac { 3 \pi } { 8 }$
C) $\cos \frac { \pi } { 8 }$
D) $\sin \frac { \pi } { 8 }$

Question

Quizplus · Accepted Answer

The cofunction identity states that $\sin(\frac{\pi}{2} - x) = \cos(x)$. Applying this to $\cos(\frac{\pi}{8})$, we get $\sin(\frac{\pi}{2} - \frac{\pi}{8}) = \sin(\frac{4\pi}{8} - \frac{\pi}{8}) = \sin(\frac{3\pi}{8})$.

Find a Cofunction with the Same Value as the Given cos⁡π8\cos \frac { \pi } { 8 }cos8π​

Find a Cofunction with the Same Value as the Given $\cos \frac { \pi } { 8 }$