theorem :: INTEGR14:57

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 = (sin . (cos . x)) * (sin . x) ) & Z = dom f & f | A is continuous holds
integral (f,A) = ((cos * cos) . (upper_bound A)) - ((cos * cos) . (lower_bound A))