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# Solution for Differentiate $\Sin^{- 1} \Left( 2 X^2 - 1 \Right), 0 < X < 1$ ? - CBSE (Science) Class 12 - Mathematics

ConceptSimple Problems on Applications of Derivatives

#### Question

Differentiate $\sin^{- 1} \left( 2 x^2 - 1 \right), 0 < x < 1$  ?

#### Solution

$\text{ Let, y } = \sin^{- 1} \left\{ 2 x^2 - 1 \right\}$

$\text{ Put x } = \cos \theta$

$y = \sin^{- 1} \left\{ 2 \cos^2 \theta - 1 \right\}$

$y = \sin^{- 1} \left( \cos2\theta \right)$

$y = \sin^{- 1} \left\{ \sin\left( \frac{\pi}{2} - 2\theta \right) \right\} . . . \left( i \right)$

$\text{ Here }, 0 < x < 1$

$\Rightarrow 0 < \cos \theta < 1$

$\Rightarrow 0 < \theta < \frac{\pi}{2}$

$\Rightarrow 0 < 2\theta < \pi$

$\Rightarrow 0 > - 2\theta > - \pi$

$\Rightarrow \frac{\pi}{2} > \left( \frac{\pi}{2} - 2\theta \right) > - \frac{\pi}{2}$

$\Rightarrow - \frac{\pi}{2} < \left( \frac{\pi}{2} - 2\theta \right) < \frac{\pi}{2}$

$\text{ So, from equation } \left( i \right),$

$y = \frac{\pi}{2} - 2\theta \left[ Since, \sin^{- 1} \left( \sin\theta \right) = \theta, if \theta \in \left[ - \frac{\pi}{2}, \frac{\pi}{2} \right] \right]$

$\Rightarrow y = \frac{\pi}{2} - 2 \cos^{- 1} x \left[ Since, x = \cos \theta \right]$

$\text{ Differentiating it with respect to x },$

$\frac{d y}{d x} = 0 - 2\frac{d}{dx}\left( \cos^{- 1} x \right)$

$\Rightarrow \frac{d y}{d x} = - 2\left( - \frac{1}{\sqrt{1 - x^2}} \right)$

$\therefore \frac{d y}{d x} = \frac{2}{\sqrt{1 - x^2}}$

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Solution Differentiate $\Sin^{- 1} \Left( 2 X^2 - 1 \Right), 0 < X < 1$ ? Concept: Simple Problems on Applications of Derivatives.
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