theorem :: INTEGR14:18

for A being non empty closed_interval Subset of REAL
for f being PartFunc of REAL,REAL
for Z being open Subset of REAL st A c= Z & ( for x being Real st x in Z holds
f . x = ((exp_R . x) * (cos . (exp_R . x))) / ((sin . (exp_R . x)) ^2) ) & Z c= dom (cosec * exp_R) & Z = dom f & f | A is continuous holds
integral (f,A) = ((- (cosec * exp_R)) . (upper_bound A)) - ((- (cosec * exp_R)) . (lower_bound A))