1. The problem statement, all variables and given/known data Verify that f has an inverse <- prof told us not to worry about this. Then use the function f and the given real number a to find (f^-1)'(a). f(x) = Cos(2x), 0<=x<=pi/2 where a=1 2. Relevant equations 1/(f'(g(x))) where g(x)=f^-1(a) d/dx(cos(2x)) = -2sin(2x) 3. The attempt at a solution Ok, I know the derivative of the function. So i take cos(2x)=1 and I get x=0. then use the derivative of cos(2x) and use the formula 1/(-2sin(2*0)) = undefined. I feel like i must be missing some detail or making a mistake. If I am not, what does it mean whenever this is undefined? is there something i can do algebraically or with a limit to make this work? Thanks P.S. sorry about the ugly math, I've tried to learn latex and it never seems to stick since I don't post many math questions.