For $x∈[1,1]$, if $4 \sin^{-1}x + \cos^{-1}x = π$ then $x$ is equal to
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $\frac{1}{2}$
$4\sin^{-1}x+\cos^{-1}x=\pi$
Use the identity:
$\cos^{-1}x=\frac{\pi}{2}-\sin^{-1}x$
Substitute:
$4\sin^{-1}x+\left(\frac{\pi}{2}-\sin^{-1}x\right)=\pi$
Combine like terms:
$3\sin^{-1}x+\frac{\pi}{2}=\pi$
So:
$3\sin^{-1}x=\frac{\pi}{2}$
$\sin^{-1}x=\frac{\pi}{6}$
Therefore:
$x=\sin\left(\frac{\pi}{6}\right)$
$x=\frac{1}{2}$