Integral 4 sin kuadrat x cos 2x dx

∫(4 . sin 2x . cos 2x) dx
= ∫(2 . 2 . sin 2x . cos 2x) dx 
= 2 . ∫(2 . sin 2x . cos 2x) dx → Rumus 2 sin α cos β = sin (α + β) + sin (α - β)
= 2 . ∫[sin (2x + 2x) + sin (2x - 2x)] dx
= 2 . ([sin 4x + sin 0°) dx
= 2 . ∫(sin 4x + 0) dx
= 2 . ∫sin 4x dx

misal u = 4x
du = 4 dx
⇔ dx =  du

= 2 . ∫sin u .  du
= 2 .  . ∫sin u du
=  . (-cos u) + c
=  . (-cos 4x) + c
= - . cos 4x + c