Question:
Evaluate the following integrals:
$\int \frac{\sqrt{\tan x}}{\sin x \cos x} d x$
Solution:
Multiply and divide by $\cos x$
$\Rightarrow \int \frac{\sqrt{\tan x} \cdot \cos x}{\sin x \cdot \cos x \cdot \cos x} d x$
$\Rightarrow \int \frac{\sqrt{\tan x}}{\tan x \cdot \cos ^{2} x} d x$
$\Rightarrow \int \frac{\sec ^{2} x}{\sqrt{\tan x}} d x$
Assume $\tan x=t$
$d(\tan x)=d t$
$\sec ^{2} x d x=d t$
Substituting $t$ and $d t$ in above equation we get
$\Rightarrow \int \frac{1}{\sqrt{t}} \mathrm{dt}$
$\Rightarrow \int \mathrm{t}^{-1 \backslash 2} \cdot \mathrm{dt}$
$\Rightarrow 2 t^{1 / 2}+c$
But $t=\tan x$
$\Rightarrow 2(\tan x)^{1 / 2}+c$