# ∫ Sin − 1 X X 2 D X - Mathematics

Sum
$\int\frac{\sin^{- 1} x}{x^2} \text{ dx }$

#### Solution

$\text{ Let I} = \int \frac{\sin^{- 1} x}{x^2} \text{ dx }$

$\text{ Putting x }= \sin \theta$

$\Rightarrow \theta = \sin^{- 1} x$

$\text{and}\ dx = \cos \text{ θ dθ }$

$\therefore I = \int \frac{\theta . \cos \theta}{\sin^2 \theta}d\theta$

$= \int \theta . \left( \frac{\cos \theta}{\sin \theta} \right) \times \frac{1}{\sin \theta} d\theta$

$= \int \theta_I . \text{ cosec} _{II} θ \cot \text{ θ dθ }$

$= \theta\int cosec \theta \cot \text{ θ dθ } - \int\left\{ \frac{d}{d\theta}\left( \theta \right)\int cosec \theta \cot \text{ θ dθ }\right\}d\theta$

$= \theta \left( - \text{ cosec }\theta \right) - \int1 . \left( - cosec \theta \right) d\theta$

$= - \theta \text{ cosec }\theta + \int cosec \text{ θ dθ }$

$= - \theta \text{ cosec }\theta + \text{ ln }\left| \text{ cosec }\theta - \cot \theta \right| + C$

$= \frac{- \theta}{\sin \theta} + \text{ ln }\left| \frac{1 - \text{ cos }\theta}{\sin \theta} \right| + C$

$= \frac{- \theta}{\sin \theta} + \text{ ln} \left| \frac{1 - \sqrt{1 - \sin^2 \theta}}{\sin \theta} \right| + C$

$= \frac{- \sin^{- 1} x}{x} + \text{ ln } \left| \frac{1 - \sqrt{1 - x^2}}{x} \right| + C \left[ \because \theta = \sin^{- 1} x \right]$

Concept: Indefinite Integral Problems
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#### APPEARS IN

RD Sharma Class 12 Maths
Chapter 19 Indefinite Integrals
Exercise 19.25 | Q 39 | Page 134