是不是这样
∫ (0->1) [ √(1-x^2)+ (1/2)x ] dx
=[∫ (0->1) √(1-x^2) dx ]+ (1/4)[x^2]|(0->1)
=1/4 +∫(0->1) √(1-x^2) dx
=1/4 +π/4
let
x=sinu
dx=cosu du
x=0, u=0
x=1, u=π/2
∫(0->1) √(1-x^2) dx
=∫(0->π/2) (cosu)^2 du
=(1/2)∫(0->π/2) (1+cos2u) du
=(1/2) [x+(1/2)sin2u]|(0->π/2)
=π/4