f(x) = 3·LN(SIN(x)/x)
f'(x) = 3/(SIN(x)/x) * (COS(x)*x - SIN(x))/x^2
f'(x) = 3*x/SIN(x) * (COS(x)*x - SIN(x))/x^2
f'(x) = 3/SIN(x) * (COS(x)*x - SIN(x))/x
f'(x) = (3·COS(x)·x - 3·SIN(x)) / (SIN(x)·x)
f'(x) = 3·COS(x)·x / (SIN(x)·x) - 3·SIN(x) / (SIN(x)·x)
f'(x) = 3·COT(x) - 3 / x