∫(0,π)sin²xdx=∫(0,π)[1-cos(2x)]/2 dx=∫(0,π)[1-cos(2x)]/4 d(2x)=(1/4)∫(0,π)[1-cos(2x)]d(2x)=(1/4) [2x-sin(2x)/2] |(0,π)=(1/4)[2π-sin(2π)/2-2×0-sin(0)/2]=(1/4)(2π)=π/2 提示：利用三角...