Evaluate: `int1/(sinx+sin2x)\ dx`

Explanation

`I=int frac{d x}{sin x+sin 2 x}`

`=int frac{d x}{sin x+2 sin x cos x}`

`=int frac{d x}{sin x(1+2 cos x)}`

`=int frac{sin x d x}{sin ^{2} x(1+2 cos x)}`

`=int frac{sin x d x}{(1-cos ^{2} x)(1+2 cos x)}`

`=int frac{sin x d x}{(1-cos x)(1+cos x)(1+2 cos x)}`

`text { Putting } cos x=t`

`Rightarrow-sin x d x=d t`

...