hasil dari int 0 sampai π/6 (2 cos 2x cos 6x)dx

InTegraL

∫(2 cos 2x cos 6x) dx [π/6...0]
= ∫(cos (2x + 6x) + cos (6x - 2x)) dx
= 1/8 ∫dsin 8x + 1/4 ∫dsin 4x
= 1/8 sin 8x + 1/4 sin 4x
= 1/8 sin 240° + 1/4 sin 120° - 0
= 1/8 (-1/2 √3) + 1/4 (1/2 √3)
= 1/2 √3 (1/4 - 1/8)
= 1/2 √3 . 1/8
= 1/16 √3 ✔