1. The problem statement, all variables and given/known data ∫ dx/ x2 (√4-x2) 2. Relevant equations x=2sinθ dx=2cosθdx sin2 θ= (1 + cos (2θ))/2 3. The attempt at a solution First attempt: Plug in the trig sub and get: ∫2cosθdθ/4sin2θ2cosθ The two cos θ cancel leaving ∫ dθ/ (4sin2θ) Now I replace the sin2θ with (1-cos2θ)/2 and get 1/2 ∫dθ/(1-cos2θ) I use u sub with the cos2θ u=2θ du/2=dθ ∫cosudu= sin2θ/2 I plug it back into the original equation 1/2 [ 2/θ-sin2θ]= 1/(θ-2sinθcosθ) I retrieve the x from the original equation to get 4/ arcsin(x/2) -(x)(√(4-x2)) I may be doing something completely wrong, but I can't figure out where. Any hint on where to find the mistake? I keep practicing trig sub problems and I can not get any right. It might have to do with the derivation of the equations, but I am not sure.