XÉT TÍNH ĐÚNG SAI sin^2x=1-cos2x/2 cos6x=2cos^23x-1 cos6x=1-2sin^23x cos3x=cos^3x-sin^3x

XÉT TÍNH ĐÚNG SAI
sin^2x = 1-cos2x/2
cos6x = 2cos^23x-1
cos6x = 1-2sin^23x
cos3x = cos^3x-sin^3x