The value of $\cos ^{-1}\left( an \left(\frac{7 \pi}{4} ight) ight)$ is

Question

The value of $\cos ^{-1}\left(	an \left(\frac{7 \pi}{4}ight)ight)$ is

Aicharya · Accepted Answer

$\begin{aligned} & \cos ^{-1}\left(	an \frac{7 \pi}{4}ight)=\cos ^{-1} 	an \left(2 \pi-\frac{\pi}{4}ight)=\cos -1\left(-	an \frac{\pi}{4}ight) \ & =\cos ^{-1}(-1) \ & =\pi\end{aligned}$

The value of $\cos ^{-1}\left(\tan \left(\frac{7 \pi}{4}\right)\right)$ is

Solution