gulaim71 (sin^2x)^3+(cos^2x)^3=(sin^2x+cos^2x)((sin^2x)^2-sin^2xcos^2x+(cos^2x)^2)= ((sin^2x+cos^2x)^2-2*sin^2xcos^2x-1/4sin^22x=1--1/2sin^22x-1/4sin^22x=1-3/4sin^22x