let f(x) = csc^2x find f\'(x) find f\'(/4) Solution Treat csc x just like any other variable squared (dy/dx x^2 = 2x) So dy/dx csc^2(x) is 2csc(x) but now you have to take the derivative of the \"inside\" function, which is csc (x): dy/dx csc(x) = -csc(x)cot(x) multiply the two and you get your answer: so f\'(x) = dy/dx (csc^2(x)) = -2csc^2(x)cot(x) so f\'(pi/4)=-2*(2)(1)=-4.