let r, e be Real; :: thesis: ( 0 < r & 0 < e implies ex n being Element of NAT st
for m being Element of NAT st n <= m holds
for x being real number st x in ].(- r),r.[ holds
( abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e & abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e ) )
assume that
A1:
r > 0
and
A2:
e > 0
; :: thesis: ex n being Element of NAT st
for m being Element of NAT st n <= m holds
for x being real number st x in ].(- r),r.[ holds
( abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e & abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e )
consider n being Element of NAT such that
A3:
for m being Element of NAT st n <= m holds
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
( abs (((((diff sin ,].(- r),r.[) . m) . (s * x)) * (x |^ m)) / (m ! )) < e & abs (((((diff cos ,].(- r),r.[) . m) . (s * x)) * (x |^ m)) / (m ! )) < e )
by A1, A2, Th23;
take
n
; :: thesis: for m being Element of NAT st n <= m holds
for x being real number st x in ].(- r),r.[ holds
( abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e & abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e )
let m be Element of NAT ; :: thesis: ( n <= m implies for x being real number st x in ].(- r),r.[ holds
( abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e & abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e ) )
assume A4:
n <= m
; :: thesis: for x being real number st x in ].(- r),r.[ holds
( abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e & abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e )
A5:
( sin is_differentiable_on m + 1,].(- r),r.[ & cos is_differentiable_on m + 1,].(- r),r.[ )
by Th21;
( dom sin = REAL & dom cos = REAL )
by FUNCT_2:def 1;
then X:
( ].(- r),r.[ c= dom sin & ].(- r),r.[ c= dom cos )
;
now let x be
Real;
:: thesis: ( x in ].(- r),r.[ implies ( abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e & abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e ) )assume A6:
x in ].(- r),r.[
;
:: thesis: ( abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e & abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e )consider s being
Real such that A7:
(
0 < s &
s < 1 )
and A8:
abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) = abs (((((diff sin ,].(- r),r.[) . (m + 1)) . (s * x)) * (x |^ (m + 1))) / ((m + 1) ! ))
by A1, A5, A6, Th4, X;
m <= m + 1
by NAT_1:11;
then A9:
n <= m + 1
by A4, XXREAL_0:2;
hence
abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e
by A3, A6, A7, A8;
:: thesis: abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < econsider s being
Real such that A10:
(
0 < s &
s < 1 )
and A11:
abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) = abs (((((diff cos ,].(- r),r.[) . (m + 1)) . (s * x)) * (x |^ (m + 1))) / ((m + 1) ! ))
by A1, A5, A6, Th4, X;
thus
abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e
by A3, A6, A9, A10, A11;
:: thesis: verum end;
hence
for x being real number st x in ].(- r),r.[ holds
( abs ((sin . x) - ((Partial_Sums (Maclaurin sin ,].(- r),r.[,x)) . m)) < e & abs ((cos . x) - ((Partial_Sums (Maclaurin cos ,].(- r),r.[,x)) . m)) < e )
; :: thesis: verum