Inverse Trigonometric Functions

The value of ${\sin }^{-1}\left[\cot \left({\sin }^{-1}\sqrt{\left(\frac{2-\sqrt{3}}{4}\right)}+{\cos }^{-1}\frac{\sqrt{12}}{4}+{\sec }^{-1}\sqrt{2}\right)\right]$ is 

If ${\sin }^{-1}a+{\sin }^{-1}b+{\sin }^{-1}c=\pi$, then the value of $a\sqrt{1-a^2}+b\sqrt{1-b^2}+c\sqrt{1-c^2}$ will be

${\cos }^{-1}\frac{1}{2}+2{\sin }^{-1}\frac{1}{2}$ is equal to