(cos x)^3 dx=cosx * (1-sin^2 x)dx=(1-sin^2 x)dsinx=sinx-1/3*sin^3 x +c
(sin x)^3 dx=sinx * (1-cos^2 x)dx=(cos^2 x -1)dcosx=1/3*cos^3 x - cosx +c
(cos x)^3 dx=cosx * (1-sin^2 x)dx=(1-sin^2 x)dsinx=sinx-1/3*sin^3 x +c
(sin x)^3 dx=sinx * (1-cos^2 x)dx=(cos^2 x -1)dcosx=1/3*cos^3 x - cosx +c