(a) Evaluate: 3 sin^-1(1/(√ 2))+2 cos^-1((√ 3)/2)+ cos^-1(0)

Given expression $\displaystyle =\frac{3 \pi}{4}+\frac{2 \pi}{6}+\frac{\pi}{2}$

$$=\frac{19 \pi}{12}

$$(b) Correct graph

Here, the points A, B, C and D are respectively $\displaystyle \left(0, \frac{\pi}{4}\right),\left(0,-\frac{\pi}{4}\right),\left(\frac{1}{\sqrt{2}}, 0\right),\left(-\frac{1}{\sqrt{2}}, 0\right)$.

Range $\displaystyle =\left[-\frac{\pi}{4}, \frac{\pi}{4}\right]$