MCQ
$\sin ^2\left(\sin ^{-1} \frac{1}{2}\right)+\tan ^2\left(\sec ^{-1} 2\right)+\cot ^2\left(\operatorname{cosec}^{-1} 4\right)=$
  • $\frac{73}{4}$
  • B
    $\frac{37}{2}$
  • C
    $\frac{89}{4}$
  • D
    $19$

Answer

Correct option: A.
$\frac{73}{4}$
(A) Let $\operatorname{cosec}^{-1} 4=\theta \Rightarrow \operatorname{cosec} \theta=4$
$\cot ^2 \theta=\operatorname{cosec}^2 \theta-1=(4)^2-1=15$
$\sin ^2\left(\sin ^{-1} \frac{1}{2}\right)+\tan ^2\left(\sec ^{-1} 2\right)+\cot ^2\left(\operatorname{cosec}^{-1} 4\right)$
$=\sin ^2 30^{\circ}+\tan ^2 60^{\circ}+\cot ^2 \theta$
$=\left(\frac{1}{2}\right)^2+(\sqrt{3})^2+15$
$=\frac{73}{4}$

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