0)所围成立体的体积.

网友回答

所围成立体的体积=∫dθ∫(β-α)r²cosθdr (作柱面坐标变换)
=(β-α)∫cosθdθ∫r²dr
=(β-α)∫[(2acosθ)³/3]cosθdθ
=[(8a³/3)(β-α)]∫cos³θdθ
=[(8a³/3)(β-α)](sinθ-sin³θ/3)│
=[(8a³/3)(β-α)](1-1/3+1-1/3)
=32a³(β-α)/9.