Có vt=cosasina.(cos^2 a -sín^2 a)
=sin2a/2(1-2sin^2 a)-
=sin2a.cos2a/2
=sin4a/4
chúc u thi tốt nha,..........,.........,..............,......,......,............,......................,.
Có vt=cosasina.(cos^2 a -sín^2 a)
=sin2a/2(1-2sin^2 a)-
=sin2a.cos2a/2
=sin4a/4
chúc u thi tốt nha,..........,.........,..............,......,......,............,......................,.