Sin^3 2a cos6a+cos^3 2a sin6a
sin^32a(4cos^32a-3cos2a)+cos^32a(3sin2a-4sin^32a)=
=4sin^32acos^32a-3cos2a*sin^32a+3sin2a*cos^32a-4sin^32acos^32a=
=3sin2acos2a(cos^22a-sin^22a)=3sin2acos2acos4a=3/2sin4acos4a=
=3/4sin8a