let a be Real; :: thesis: for A being closed-interval Subset of REAL
for f1, f being PartFunc of REAL ,REAL
for Z being open Subset of REAL st A c= Z & Z c= dom (cot * f1) & f = ((cos * f1) ^2 ) / ((sin * f1) ^2 ) & ( for x being Real st x in Z holds
( f1 . x = a * x & a <> 0 ) ) & Z = dom f holds
integral f,A = ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (sup A)) - ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (inf A))
let A be closed-interval Subset of REAL ; :: thesis: for f1, f being PartFunc of REAL ,REAL
for Z being open Subset of REAL st A c= Z & Z c= dom (cot * f1) & f = ((cos * f1) ^2 ) / ((sin * f1) ^2 ) & ( for x being Real st x in Z holds
( f1 . x = a * x & a <> 0 ) ) & Z = dom f holds
integral f,A = ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (sup A)) - ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (inf A))
let f1, f be PartFunc of REAL ,REAL ; :: thesis: for Z being open Subset of REAL st A c= Z & Z c= dom (cot * f1) & f = ((cos * f1) ^2 ) / ((sin * f1) ^2 ) & ( for x being Real st x in Z holds
( f1 . x = a * x & a <> 0 ) ) & Z = dom f holds
integral f,A = ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (sup A)) - ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (inf A))
let Z be open Subset of REAL ; :: thesis: ( A c= Z & Z c= dom (cot * f1) & f = ((cos * f1) ^2 ) / ((sin * f1) ^2 ) & ( for x being Real st x in Z holds
( f1 . x = a * x & a <> 0 ) ) & Z = dom f implies integral f,A = ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (sup A)) - ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (inf A)) )
assume A1: ( A c= Z & Z c= dom (cot * f1) & f = ((cos * f1) ^2 ) / ((sin * f1) ^2 ) & ( for x being Real st x in Z holds
( f1 . x = a * x & a <> 0 ) ) & Z = dom f ) ; :: thesis: integral f,A = ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (sup A)) - ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (inf A))
A2: Z c= dom ((- (1 / a)) (#) (cot * f1)) by VALUED_1:def 5, A1;
dom (id Z) = Z by RELAT_1:71;
then A3: Z c= (dom ((- (1 / a)) (#) (cot * f1))) /\ (dom (id Z)) by XBOOLE_1:19, A2;
A4: Z c= dom (((- (1 / a)) (#) (cot * f1)) - (id Z)) by VALUED_1:12, A3;
A5: for x being Real st x in Z holds
f1 . x = (a * x) + 0 by A1;
A6: Z = (dom ((cos * f1) ^2 )) /\ ((dom ((sin * f1) ^2 )) \ (((sin * f1) ^2 ) " {0 })) by A1, RFUNCT_1:def 4;
A7: ( Z c= dom ((cos * f1) ^2 ) & Z c= (dom ((sin * f1) ^2 )) \ (((sin * f1) ^2 ) " {0 }) ) by XBOOLE_1:18, A6;
A8: Z c= dom (cos * f1) by VALUED_1:11, A7;
A9: Z c= dom (((sin * f1) ^2 ) ^ ) by RFUNCT_1:def 8, A7;
dom (((sin * f1) ^2 ) ^ ) c= dom ((sin * f1) ^2 ) by RFUNCT_1:11;
then A10: Z c= dom ((sin * f1) ^2 ) by XBOOLE_1:1, A9;
A11: Z c= dom (sin * f1) by VALUED_1:11, A10;
A12: sin * f1 is_differentiable_on Z by FDIFF_4:37, A11, A5;
A13: cos * f1 is_differentiable_on Z by FDIFF_4:38, A5, A8;
A15: (sin * f1) ^2 is_differentiable_on Z by FDIFF_2:20, A12;
A17: (cos * f1) ^2 is_differentiable_on Z by FDIFF_2:20, A13;
A18: for x being Real st x in Z holds
((sin * f1) ^2 ) . x <> 0

proof

let x be Real; :: thesis: ( x in Z implies ((sin * f1) ^2 ) . x <> 0 )
assume x in Z ; :: thesis: ((sin * f1) ^2 ) . x <> 0
then x in (dom ((cos * f1) ^2 )) /\ ((dom ((sin * f1) ^2 )) \ (((sin * f1) ^2 ) " {0 })) by A1, RFUNCT_1:def 4;
then x in (dom ((sin * f1) ^2 )) \ (((sin * f1) ^2 ) " {0 }) by XBOOLE_0:def 4;
then x in dom (((sin * f1) ^2 ) ^ ) by RFUNCT_1:def 8;
hence ((sin * f1) ^2 ) . x <> 0 by RFUNCT_1:13; :: thesis: verum

end;

A19: f is_differentiable_on Z by A1, A15, A17, A18, FDIFF_2:21;
f | Z is continuous by A19, FDIFF_1:33;
then A20: f | A is continuous by A1, FCONT_1:17;
A21: ( f is_integrable_on A & f | A is bounded ) by A1, A20, INTEGRA5:10, INTEGRA5:11;
A22: ((- (1 / a)) (#) (cot * f1)) - (id Z) is_differentiable_on Z by A1, A4, FDIFF_8:27;
B1: for x being Real st x in Z holds
f . x = ((cos . (a * x)) ^2 ) / ((sin . (a * x)) ^2 )

proof

let x be Real; :: thesis: ( x in Z implies f . x = ((cos . (a * x)) ^2 ) / ((sin . (a * x)) ^2 ) )
assume B2: x in Z ; :: thesis: f . x = ((cos . (a * x)) ^2 ) / ((sin . (a * x)) ^2 )
(((cos * f1) ^2 ) / ((sin * f1) ^2 )) . x = (((cos * f1) ^2 ) . x) / (((sin * f1) ^2 ) . x) by RFUNCT_1:def 4, A1, B2
.= (((cos * f1) . x) ^2 ) / (((sin * f1) ^2 ) . x) by VALUED_1:11
.= (((cos * f1) . x) ^2 ) / (((sin * f1) . x) ^2 ) by VALUED_1:11
.= ((cos . (f1 . x)) ^2 ) / (((sin * f1) . x) ^2 ) by FUNCT_1:22, A8, B2
.= ((cos . (f1 . x)) ^2 ) / ((sin . (f1 . x)) ^2 ) by FUNCT_1:22, A11, B2
.= ((cos . (a * x)) ^2 ) / ((sin . (f1 . x)) ^2 ) by B2, A1
.= ((cos . (a * x)) ^2 ) / ((sin . (a * x)) ^2 ) by B2, A1 ;
hence f . x = ((cos . (a * x)) ^2 ) / ((sin . (a * x)) ^2 ) by A1; :: thesis: verum

end;

A23: for x being Real st x in dom ((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) holds
((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) . x = f . x

proof

let x be Real; :: thesis: ( x in dom ((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) implies ((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) . x = f . x )
assume x in dom ((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) ; :: thesis: ((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) . x = f . x
then A24: x in Z by A22, FDIFF_1:def 8;
then ((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) . x = ((cos . (a * x)) ^2 ) / ((sin . (a * x)) ^2 ) by A1, A4, FDIFF_8:27
.= f . x by B1, A24 ;
hence ((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) . x = f . x ; :: thesis: verum

end;

dom ((((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z) = dom f by A1, A22, FDIFF_1:def 8;
then (((- (1 / a)) (#) (cot * f1)) - (id Z)) `| Z = f by A23, PARTFUN1:34;
hence integral f,A = ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (sup A)) - ((((- (1 / a)) (#) (cot * f1)) - (id Z)) . (inf A)) by A1, A21, A22, INTEGRA5:13; :: thesis: verum