∫(cos x)^3dx=?上限是二分之派,下限是负的二分之派.
问题描述：
∫(cos x)^3dx=?上限是二分之派,下限是负的二分之派.
答
∫[-π/2,π/2](cos x)^3dx
=∫[-π/2,π/2](1-sin^2x)dsinx
=(sinx-1/3sin^3x)[-π/2,π/2]
=1-1/3+1-1/3
=4/3