-3 ln |cos x/3| + C
Пошаговое объяснение:
∫ tg x/3 dx = ∫ sin x/3 / cos x/3 dx = =
d(cos x/3) = - 1/3 sin x/3 dx > sin x/3 dx = -3 d(cos x/3)
= = ∫ -3 d(cos x/3) / cos x/3 =
= -3 ∫d(cos x/3) / cos x/3 =
= -3 ln |cos x/3| + C
