1. The problem statement, all variables and given/known data Integrate the following using substitution techniques ∫e3tcsc(e3t)cot(e3t) dt 2. Relevant equations csc(t) = 1/sin(t) cot(t) = 1/tan(t) cot(t) = cos(t)/sin(t) 1 + cot2(t) = csc2(t) 3. The attempt at a solution ∫e3tcsc(e3t)cot(e3t) dt set u = cot(e3t) du = (3e3t)(- csc2(e3t)) dt Make Substitution, ∫e3tcsc(e3t) (u) (1/(3e3t)(- csc2(e3t)) du Whoops, csc does not cancel out.. My friend told me I had to make TWO substitutions, following this advice my head proceeded to explode. After recollecting the pieces of my skull fragments and carefully gluing them together again, I posted this question.