Find $\int \frac{dx}{\sqrt{\sin^3 x \cos(x - \alpha)}}$.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $-2 \frac{\sqrt{\cot x \cos \alpha + \sin \alpha}}{\sqrt{\cos \alpha}} + c$
$\int \frac{dx}{\sqrt{\sin^3 x \cos(x - \alpha)}}=\int \frac{dx}{\sqrt{\sin^3 x (\cos x \cos \alpha + \sin x \sin \alpha)}}$
$= \int \frac{dx}{\sin^2 x \sqrt{\frac{\cos x}{\sin x} \cos \alpha + \sin \alpha}}$
$= \int \frac{\text{cosec}^2 x \, dx}{\sqrt{\cot x \cos \alpha + \sin \alpha}}$
$=\frac{1}{\sqrt{\cos \alpha}}\int \frac{\text{cosec}^2 x \, dx}{\cot x+\tan \alpha}$
Let $\cot x +\tan \alpha=t$
$-\text{cosec}^2 x dx=dt$
$= \frac{1}{\sqrt{\cos \alpha}} \int \frac{-dt}{\sqrt{t}}$
$= -\frac{2\sqrt{t}}{\sqrt{\cos \alpha}} + c$
$=-2 \frac{\sqrt{\cot x \cos \alpha + \sin \alpha}}{\sqrt{\cos \alpha}} + c$