(sinx-cosx)^2=(sinx)^2-2sinxcosx+(cosx)^2=1-sin(2x)=1/9 sin(2x)=1-1/9=8/9 (sinx)^3-(cosx)^3 =(sinx-cosx)[(sinx)^2+sinxcosx+(cosx)^2] =(1/3)[1+sin(2x)/2] =(1/3)(1+4/9) =13/27
