How do you find the integral of cotx5cscx2?

1 Answer
Mar 5, 2015

Our required integral is,

I=cot5xcsc2xdx

First, we make the substitution,

cotx=t

If we differentiate both sides with respect to t,

ddt(cotx)=dtdt

Then we get,

(csc2x)dxdt=1

On rearraging,

csc2xdx=dt

On substituting these values in our original integral, we get

I=t5dt

which can be solved trivially to get the solution

t66+C

On substituting the value of t=cotx, we get,

I=cot6x6+C

In case your question was cotx5cscx2dx the answer is far more complicated and beyond the scope of a straight-forward pen and paper solution. Maybe, the solution does not even exist.