MCQ
$\cos \left[2 \cos ^{-1} \frac{1}{5}+\sin ^{-1} \frac{1}{5}\right]=$
  • A
    $\frac{2 \sqrt{6}}{5}$
  • $-\frac{2 \sqrt{6}}{5}$
  • C
    $\frac{1}{5}$
  • D
    $-\frac{1}{5}$

Answer

Correct option: B.
$-\frac{2 \sqrt{6}}{5}$
(B) $\cos \left(\cos ^{-1} \frac{1}{5}+\sin ^{-1} \frac{1}{5}+\cos ^{-1} \frac{1}{5}\right)$
$=\cos \left(\frac{\pi}{2}+\cos ^{-1} \frac{1}{5}\right)=-\sin \left(\cos ^{-1} \frac{1}{5}\right)$
$=-\sin \left(\sin ^{-1} \sqrt{\frac{24}{25}}\right)$
$=-\frac{2 \sqrt{6}}{5}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free