let n be Element of NAT ; :: thesis: for A being closed-interval Subset of REAL
for f being PartFunc of REAL,REAL
for Z being open Subset of REAL st A c= Z & f = (n (#) ((#Z (n - 1)) * sin)) / ((#Z (n + 1)) * cos) & 1 <= n & Z c= dom ((#Z n) * tan) & Z = dom f holds
integral (f,A) = (((#Z n) * tan) . (upper_bound A)) - (((#Z n) * tan) . (lower_bound A))
let A be closed-interval Subset of REAL; :: thesis: for f being PartFunc of REAL,REAL
for Z being open Subset of REAL st A c= Z & f = (n (#) ((#Z (n - 1)) * sin)) / ((#Z (n + 1)) * cos) & 1 <= n & Z c= dom ((#Z n) * tan) & Z = dom f holds
integral (f,A) = (((#Z n) * tan) . (upper_bound A)) - (((#Z n) * tan) . (lower_bound A))
let f be PartFunc of REAL,REAL; :: thesis: for Z being open Subset of REAL st A c= Z & f = (n (#) ((#Z (n - 1)) * sin)) / ((#Z (n + 1)) * cos) & 1 <= n & Z c= dom ((#Z n) * tan) & Z = dom f holds
integral (f,A) = (((#Z n) * tan) . (upper_bound A)) - (((#Z n) * tan) . (lower_bound A))
let Z be open Subset of REAL; :: thesis: ( A c= Z & f = (n (#) ((#Z (n - 1)) * sin)) / ((#Z (n + 1)) * cos) & 1 <= n & Z c= dom ((#Z n) * tan) & Z = dom f implies integral (f,A) = (((#Z n) * tan) . (upper_bound A)) - (((#Z n) * tan) . (lower_bound A)) )
assume A1: ( A c= Z & f = (n (#) ((#Z (n - 1)) * sin)) / ((#Z (n + 1)) * cos) & 1 <= n & Z c= dom ((#Z n) * tan) & Z = dom f ) ; :: thesis: integral (f,A) = (((#Z n) * tan) . (upper_bound A)) - (((#Z n) * tan) . (lower_bound A))
then Z = (dom (n (#) ((#Z (n - 1)) * sin))) /\ ((dom ((#Z (n + 1)) * cos)) \ (((#Z (n + 1)) * cos) " {0})) by RFUNCT_1:def 4;
then A3: ( Z c= dom (n (#) ((#Z (n - 1)) * sin)) & Z c= (dom ((#Z (n + 1)) * cos)) \ (((#Z (n + 1)) * cos) " {0}) ) by XBOOLE_1:18;
then A4: Z c= dom (((#Z (n + 1)) * cos) ^) by RFUNCT_1:def 8;
dom (((#Z (n + 1)) * cos) ^) c= dom ((#Z (n + 1)) * cos) by RFUNCT_1:11;
then A5: Z c= dom ((#Z (n + 1)) * cos) by A4, XBOOLE_1:1;
A6: for x being Real st x in Z holds
((#Z (n + 1)) * cos) . x <> 0

proof

let x be Real; :: thesis: ( x in Z implies ((#Z (n + 1)) * cos) . x <> 0 )
assume x in Z ; :: thesis: ((#Z (n + 1)) * cos) . x <> 0
then x in (dom (n (#) ((#Z (n - 1)) * sin))) /\ ((dom ((#Z (n + 1)) * cos)) \ (((#Z (n + 1)) * cos) " {0})) by A1, RFUNCT_1:def 4;
then x in (dom ((#Z (n + 1)) * cos)) \ (((#Z (n + 1)) * cos) " {0}) by XBOOLE_0:def 4;
then x in dom (((#Z (n + 1)) * cos) ^) by RFUNCT_1:def 8;
hence ((#Z (n + 1)) * cos) . x <> 0 by RFUNCT_1:13; :: thesis: verum

end;

A9: Z c= dom ((#Z (n - 1)) * sin) by VALUED_1:def 5, A3;
A10: for x being Real holds (#Z (n - 1)) * sin is_differentiable_in x

proof

let x be Real; :: thesis: (#Z (n - 1)) * sin is_differentiable_in x
consider m being Nat such that
A11: n = m + 1 by A1, NAT_1:6;
sin is_differentiable_in x by SIN_COS:69;
hence (#Z (n - 1)) * sin is_differentiable_in x by A11, TAYLOR_1:3; :: thesis: verum

end;

(#Z (n - 1)) * sin is_differentiable_on Z

proof

for x being Real st x in Z holds
(#Z (n - 1)) * sin is_differentiable_in x by A10;
hence (#Z (n - 1)) * sin is_differentiable_on Z by A9, FDIFF_1:16; :: thesis: verum

end;

then A15: n (#) ((#Z (n - 1)) * sin) is_differentiable_on Z by A3, FDIFF_1:28;
A16: for x being Real holds (#Z (n + 1)) * cos is_differentiable_in x

proof

let x be Real; :: thesis: (#Z (n + 1)) * cos is_differentiable_in x
cos is_differentiable_in x by SIN_COS:68;
hence (#Z (n + 1)) * cos is_differentiable_in x by TAYLOR_1:3; :: thesis: verum

end;

(#Z (n + 1)) * cos is_differentiable_on Z

proof

for x being Real st x in Z holds
(#Z (n + 1)) * cos is_differentiable_in x by A16;
hence (#Z (n + 1)) * cos is_differentiable_on Z by A5, FDIFF_1:16; :: thesis: verum

end;

then f | Z is continuous by FDIFF_1:33, A1, A6, A15, FDIFF_2:21;
then f | A is continuous by A1, FCONT_1:17;
then A22: ( f is_integrable_on A & f | A is bounded ) by A1, INTEGRA5:10, INTEGRA5:11;
A23: (#Z n) * tan is_differentiable_on Z by A1, FDIFF_8:20;
B1: for x being Real st x in Z holds
f . x = (n * ((sin . x) #Z (n - 1))) / ((cos . x) #Z (n + 1))

proof

let x be Real; :: thesis: ( x in Z implies f . x = (n * ((sin . x) #Z (n - 1))) / ((cos . x) #Z (n + 1)) )
assume B2: x in Z ; :: thesis: f . x = (n * ((sin . x) #Z (n - 1))) / ((cos . x) #Z (n + 1))
then ((n (#) ((#Z (n - 1)) * sin)) / ((#Z (n + 1)) * cos)) . x = ((n (#) ((#Z (n - 1)) * sin)) . x) / (((#Z (n + 1)) * cos) . x) by RFUNCT_1:def 4, A1
.= (n * (((#Z (n - 1)) * sin) . x)) / (((#Z (n + 1)) * cos) . x) by VALUED_1:6
.= (n * ((#Z (n - 1)) . (sin . x))) / (((#Z (n + 1)) * cos) . x) by FUNCT_1:22, A9, B2
.= (n * ((sin . x) #Z (n - 1))) / (((#Z (n + 1)) * cos) . x) by TAYLOR_1:def 1
.= (n * ((sin . x) #Z (n - 1))) / ((#Z (n + 1)) . (cos . x)) by FUNCT_1:22, A5, B2
.= (n * ((sin . x) #Z (n - 1))) / ((cos . x) #Z (n + 1)) by TAYLOR_1:def 1 ;
hence f . x = (n * ((sin . x) #Z (n - 1))) / ((cos . x) #Z (n + 1)) by A1; :: thesis: verum

end;

A24: for x being Real st x in dom (((#Z n) * tan) `| Z) holds
(((#Z n) * tan) `| Z) . x = f . x

proof

let x be Real; :: thesis: ( x in dom (((#Z n) * tan) `| Z) implies (((#Z n) * tan) `| Z) . x = f . x )
assume x in dom (((#Z n) * tan) `| Z) ; :: thesis: (((#Z n) * tan) `| Z) . x = f . x
then A25: x in Z by A23, FDIFF_1:def 8;
then (((#Z n) * tan) `| Z) . x = (n * ((sin . x) #Z (n - 1))) / ((cos . x) #Z (n + 1)) by A1, FDIFF_8:20
.= f . x by B1, A25 ;
hence (((#Z n) * tan) `| Z) . x = f . x ; :: thesis: verum

end;

dom (((#Z n) * tan) `| Z) = dom f by A1, A23, FDIFF_1:def 8;
then ((#Z n) * tan) `| Z = f by A24, PARTFUN1:34;
hence integral (f,A) = (((#Z n) * tan) . (upper_bound A)) - (((#Z n) * tan) . (lower_bound A)) by A1, A22, FDIFF_8:20, INTEGRA5:13; :: thesis: verum