前>>420訂正。
V=2∫[x=π/2→π/4](4cos3θ-3cosθ)(3cosθ-4cos3θ/3)dθ-2∫[θ=π/2→π/4](3sinθ-4sin3θ)(3cosθ-4cos3θ/3)dθ
=2(4sin3θ/3-3sinθ)(3cosθ-4cos3θ/3)(x=π/4)-2∫[θ=π/2→π/4](4sin3θ/3-3sinθ)(-3sinθ+4sin3θ)dθ
-2(-3cosθ+4cos3θ/3)(3cosθ-4cos3θ/3)(x=π/4)+2∫[θ=π/2→π/4](-3cosθ+4cos3θ/3)(-3sinθ+4sin3θ)dθ