If $a=\sin^{-1}\big(\large\frac{-1}{\sqrt 2}\big)+$$\cos^{-1}\big(\large\frac{-1}{2}\big),$$b=\tan^{-1}\big(-\sqrt 3\big)-\cot^{-1}\big(-\large\frac{1}{\sqrt 3}\big)$ then

Question

$\begin{array}{1 1}(a)\;a-b=\large\frac{17\pi}{12}&(b)\;a+b=\large\frac{17\pi}{12}\\(c)\;a+b=\large\frac{7\pi}{12}&(d)\;a-b=\large\frac{\pi}{12}\end{array}$