theorem Th3: :: INTEGR14:3

for Z being open Subset of REAL st Z c= dom (cosec * ln) holds
( - (cosec * ln) is_differentiable_on Z & ( for x being Real st x in Z holds
((- (cosec * ln)) `| Z) . x = (cos . (ln . x)) / (x * ((sin . (ln . x)) ^2)) ) )