C = (2/√3)arctan[(2x+1)/√3] + C 原式= (√3/2)∫sec²θ/(3/4*sec²θ)² dθarccost +C =arccos(1/x)+C分母 x^2 * (1+x^2)^(1/2) = t^(-2) * ( 1+1/ t^2 )^(1/2) = t^(-3)
