# The most general value of $\theta$ which satisfies both the equations $\tan \theta=-1$ and $\cos \theta=\large\frac{1}{\sqrt 2}$ is :

$\begin {array} {1 1} (a)\;n \pi+7 \frac{\pi}{4} & \quad (b)\;2n\pi+\frac{7\pi}{4} \\ (c)\;n \pi+(-1)^n \frac{7 \pi}{4} & \quad (d)\; \frac{7 n \pi}{4} \end {array}$Here n is any integer

$(b)\;2n\pi+\frac{7\pi}{4}$