3sin^2x*cos^2x=3(sinx*cosx)^2=3(1/2*2sinx*cosx)=3(1/2*sin2x)^2=3/4sin^2(2x)
sin^2+cos^2=1 sin2x=2sinx*cosx
3sin^2x*cos^2x=3(sinx*cosx)^2=3(1/2*2sinx*cosx)=3(1/2*sin2x)^2=3/4sin^2(2x)
sin^2+cos^2=1 sin2x=2sinx*cosx