Здравствуйте, помогите, пожалуйста, найти интеграл
int pi * cos (pi * x)/sin (pi * x) dx

int pi * cos (pi * x)/sin (pi * x) dx = int cos (pi * x)/sin (pi * x) d(pi * x) =
= | pi * x = t | = int cos t/sin t dt = int 1/sin t d(sin t) = | sin t = u | =
= int 1/u du = ln |u| + C = | u = sin t | = ln |sin t| + C = | t = pi * x | =
= ln |sin (pi * x)| + C