Rút gọn biểu thức sau:
A=4sinx*cosx*cos2x*cos4x
B=cos^4x -6cos^x*sin^2x+sim^4x
C=cos2a-cos4asin4a+sin2acos2a-cos4asin4a+sin2a
D=cosa+cos3a+cos5asina+sin3a+sin5acosa+cos3a+cos5asina+sin3a+sin5a
E=sin^2(π8π8+x2x2)-sin^2(π8π8-x2x2)
F=1+cosx+cos2x+cos3x2cos2x+cosx−1
