theorem :: INTEGR14:25

for A being non empty closed_interval Subset of REAL
for Z being open Subset of REAL st A c= Z & Z c= dom (ln * cosec) & Z = dom cot & cot | A is continuous holds
integral (cot,A) = ((- (ln * cosec)) . (upper_bound A)) - ((- (ln * cosec)) . (lower_bound A))