用定积分
y=x^2与x=y^2的交点(0,1)(1,1)
面积=∫[0,1] (√x-x^2)dx
=[2/3x^(3/2)-x^3/3][0,1]
=1/3
体积=∫[0,1] π[(√x)^2-(x^2)^2]dx
=π(x^2/2-x^5/5)[0,1]
=3π/10