1. The problem statement, all variables and given/known data Integral, from 0 to 1, of dx/root(1-x^2) 2. Relevant equations d/dx of arcsin = 1/root(1-x^2) 3. The attempt at a solution Since d/dx of arcsin = 1/root(1-x^2), we have that the integral, from 0 to 1, of dx/root(1-x^2) equals to arcsin, from 0 to 1. arcsin(1) - arcsin(0) = arcsin(1). I know I'm missing something here. What did I do wrong?