1. The problem statement, all variables and given/known data Show that: ∫f(sin(x))dx = ∫f(cos(x))dx where each integral is over the limits [0, [itex]\pi[/itex]/2], for a 'well behaved' function f. 2. The attempt at a solution I have tried relating sin(x) and cos(x) and somehow rearrange one of the integrals to look like the other. Since: sin(x) = cos(x-[itex]\pi[/itex]/2) I can substitute this into the LHS integral and I am sure this is the correct way to start. It is at this point where I cannot think of any way of moving forward. Any help would be appreciated.