Tentukan nilai dari: A. Cos 4a Cos 2a B. 6 Cos (x +Π/3) sih (x-Π/3) C. 2 sin 2(p+q) sin 2(p-q)

jawab

a.
cos 4A  cos 2A =
= 1/2 ( 2 cos 4A cos 2A)
= 1/2 (cos 6A - cos 2A)

b. 
6 cos (x + π/3) sin ( x- π/3) = 
3  {sin 2x - sin 2π/3)
3  (sin 2x -  sin 120)
=  3 (sin 2x - 1/2 √3)
= 3 sn 2x - 3/2 √3)

c.
2 sin 2(p+q) sin 2(p-q)
= - (cos 2(2p) - cos 2(2q)
= cos 4q - cos 4p