Question:
Evaluate the following integrals:
$\int \frac{\sin x-\cos x}{\sqrt{\sin 2 x}} d x$
Solution:
$\left.\int \frac{\sin x-\cos x}{\sqrt{\sin 2 x}} d x=\int(\sin x-\cos x) / \sqrt{(}(\sin x+\cos x)^{2}-1\right) d x$
Let $\sin x+\cos x=t$
$(\cos x-\sin x)=d t$
Therefore, $\int \frac{\sin x-\cos x}{\sqrt{(\sin x+\cos x)^{2}-1}} d x=\int-\frac{d t}{\sqrt{t^{2}-1}}$
Since, $\int \frac{1}{\sqrt{\left(x^{2}-a^{2}\right)}} d x=\log \left[x+\sqrt{\left(x^{2}-a^{2}\right)}\right]+c$
$=\int-\frac{d t}{\sqrt{t^{2}-1}}=-\log \left[t+\sqrt{t^{2}-1}\right]+c$
$=-\log \left[t+\sqrt{t^{2}-1}\right]+c=-\log [\sin x+\cos x+\sqrt{\sin 2 x}]+c$