LIST I

LIST II

 A. If $4 \sin ^{-1} x+\cos ^{-1} x=\pi$, then x equal to 

 I. $\frac{\pi}{2}$ 

 B. The value of $\frac{1-\tan ^2 15°}{1+\tan ^2 15°}$ is 

 II. $\frac{1}{2}$ 

 C. If $x+\frac{1}{x}=2$, then principal value of $\sin ^{-1} x$ is 

 III. $\frac{3 \pi}{4}$ 

 D. Two angles of a triangle are $\cot ^{-1} 2$ and $\cot ^{-1} 3$, then third angle is 

 IV. $\frac{\sqrt{3}}{2}$