Evaluate: `intcos e c^4\ 2x\ dx`

Explanation

`I = int cosec^42x dx = int cosec^22x (1+cot^22x) dx`

` = ∫ cosec^22x dx + ∫cosec^22x cot^22x dx`

`cot2x = t`

`-2.cosec^22x dx = dt`

`=-frac{cot 2x}{2}-1/2(t^2)`

`=-frac{cot 2x}{2}-1/6.(cot2x)^3`