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Theorem pythagtriplem13 12289
Description: Lemma for pythagtrip 12296. Show that  N (which will eventually be closely related to the  n in the final statement) is a natural. (Contributed by Scott Fenton, 17-Apr-2014.) (Revised by Mario Carneiro, 19-Apr-2014.)
Hypothesis
Ref Expression
pythagtriplem13.1  |-  N  =  ( ( ( sqr `  ( C  +  B
) )  -  ( sqr `  ( C  -  B ) ) )  /  2 )
Assertion
Ref Expression
pythagtriplem13  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  N  e.  NN )

Proof of Theorem pythagtriplem13
StepHypRef Expression
1 pythagtriplem13.1 . 2  |-  N  =  ( ( ( sqr `  ( C  +  B
) )  -  ( sqr `  ( C  -  B ) ) )  /  2 )
2 pythagtriplem9 12286 . . . . . 6  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( sqr `  ( C  +  B ) )  e.  NN )
32nnzd 9387 . . . . 5  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( sqr `  ( C  +  B ) )  e.  ZZ )
4 simp3r 1027 . . . . . . 7  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  -.  2  ||  A )
5 2z 9294 . . . . . . . . . 10  |-  2  e.  ZZ
6 simp3 1000 . . . . . . . . . . . . 13  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  C  e.  NN )
7 simp2 999 . . . . . . . . . . . . 13  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  B  e.  NN )
86, 7nnaddcld 8980 . . . . . . . . . . . 12  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  +  B )  e.  NN )
98nnzd 9387 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  +  B )  e.  ZZ )
1093ad2ant1 1019 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( C  +  B )  e.  ZZ )
11 nnz 9285 . . . . . . . . . . . 12  |-  ( A  e.  NN  ->  A  e.  ZZ )
12113ad2ant1 1019 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  A  e.  ZZ )
13123ad2ant1 1019 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  A  e.  ZZ )
14 dvdsgcdb 12027 . . . . . . . . . 10  |-  ( ( 2  e.  ZZ  /\  ( C  +  B
)  e.  ZZ  /\  A  e.  ZZ )  ->  ( ( 2  ||  ( C  +  B
)  /\  2  ||  A )  <->  2  ||  ( ( C  +  B )  gcd  A
) ) )
155, 10, 13, 14mp3an2i 1352 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( 2  ||  ( C  +  B )  /\  2  ||  A )  <->  2  ||  ( ( C  +  B )  gcd  A ) ) )
1615biimpar 297 . . . . . . . 8  |-  ( ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  (
( A ^ 2 )  +  ( B ^ 2 ) )  =  ( C ^
2 )  /\  (
( A  gcd  B
)  =  1  /\ 
-.  2  ||  A
) )  /\  2  ||  ( ( C  +  B )  gcd  A
) )  ->  (
2  ||  ( C  +  B )  /\  2  ||  A ) )
1716simprd 114 . . . . . . 7  |-  ( ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  (
( A ^ 2 )  +  ( B ^ 2 ) )  =  ( C ^
2 )  /\  (
( A  gcd  B
)  =  1  /\ 
-.  2  ||  A
) )  /\  2  ||  ( ( C  +  B )  gcd  A
) )  ->  2  ||  A )
184, 17mtand 666 . . . . . 6  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  -.  2  ||  ( ( C  +  B )  gcd 
A ) )
19 pythagtriplem7 12284 . . . . . . 7  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( sqr `  ( C  +  B ) )  =  ( ( C  +  B )  gcd  A
) )
2019breq2d 4027 . . . . . 6  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
2  ||  ( sqr `  ( C  +  B
) )  <->  2  ||  ( ( C  +  B )  gcd  A
) ) )
2118, 20mtbird 674 . . . . 5  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  -.  2  ||  ( sqr `  ( C  +  B )
) )
22 pythagtriplem8 12285 . . . . . 6  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( sqr `  ( C  -  B ) )  e.  NN )
2322nnzd 9387 . . . . 5  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( sqr `  ( C  -  B ) )  e.  ZZ )
24 nnz 9285 . . . . . . . . . . . . 13  |-  ( C  e.  NN  ->  C  e.  ZZ )
25243ad2ant3 1021 . . . . . . . . . . . 12  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  C  e.  ZZ )
26 nnz 9285 . . . . . . . . . . . . 13  |-  ( B  e.  NN  ->  B  e.  ZZ )
27263ad2ant2 1020 . . . . . . . . . . . 12  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  B  e.  ZZ )
2825, 27zsubcld 9393 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  -  B )  e.  ZZ )
29283ad2ant1 1019 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( C  -  B )  e.  ZZ )
30 dvdsgcdb 12027 . . . . . . . . . 10  |-  ( ( 2  e.  ZZ  /\  ( C  -  B
)  e.  ZZ  /\  A  e.  ZZ )  ->  ( ( 2  ||  ( C  -  B
)  /\  2  ||  A )  <->  2  ||  ( ( C  -  B )  gcd  A
) ) )
315, 29, 13, 30mp3an2i 1352 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( 2  ||  ( C  -  B )  /\  2  ||  A )  <->  2  ||  ( ( C  -  B )  gcd  A ) ) )
3231biimpar 297 . . . . . . . 8  |-  ( ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  (
( A ^ 2 )  +  ( B ^ 2 ) )  =  ( C ^
2 )  /\  (
( A  gcd  B
)  =  1  /\ 
-.  2  ||  A
) )  /\  2  ||  ( ( C  -  B )  gcd  A
) )  ->  (
2  ||  ( C  -  B )  /\  2  ||  A ) )
3332simprd 114 . . . . . . 7  |-  ( ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  (
( A ^ 2 )  +  ( B ^ 2 ) )  =  ( C ^
2 )  /\  (
( A  gcd  B
)  =  1  /\ 
-.  2  ||  A
) )  /\  2  ||  ( ( C  -  B )  gcd  A
) )  ->  2  ||  A )
344, 33mtand 666 . . . . . 6  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  -.  2  ||  ( ( C  -  B )  gcd 
A ) )
35 pythagtriplem6 12283 . . . . . . 7  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( sqr `  ( C  -  B ) )  =  ( ( C  -  B )  gcd  A
) )
3635breq2d 4027 . . . . . 6  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
2  ||  ( sqr `  ( C  -  B
) )  <->  2  ||  ( ( C  -  B )  gcd  A
) ) )
3734, 36mtbird 674 . . . . 5  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  -.  2  ||  ( sqr `  ( C  -  B )
) )
38 omoe 11914 . . . . 5  |-  ( ( ( ( sqr `  ( C  +  B )
)  e.  ZZ  /\  -.  2  ||  ( sqr `  ( C  +  B
) ) )  /\  ( ( sqr `  ( C  -  B )
)  e.  ZZ  /\  -.  2  ||  ( sqr `  ( C  -  B
) ) ) )  ->  2  ||  (
( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) ) )
393, 21, 23, 37, 38syl22anc 1249 . . . 4  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  2  ||  ( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) ) )
4028zred 9388 . . . . . . . . . 10  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  -  B )  e.  RR )
41403ad2ant1 1019 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( C  -  B )  e.  RR )
42 simp13 1030 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  C  e.  NN )
4342nnred 8945 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  C  e.  RR )
448nnred 8945 . . . . . . . . . 10  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  +  B )  e.  RR )
45443ad2ant1 1019 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( C  +  B )  e.  RR )
46 nnrp 9676 . . . . . . . . . . . 12  |-  ( B  e.  NN  ->  B  e.  RR+ )
47463ad2ant2 1020 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  B  e.  RR+ )
48473ad2ant1 1019 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  B  e.  RR+ )
4943, 48ltsubrpd 9742 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( C  -  B )  <  C )
50 nngt0 8957 . . . . . . . . . . . 12  |-  ( B  e.  NN  ->  0  <  B )
51503ad2ant2 1020 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  0  <  B )
52513ad2ant1 1019 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  0  <  B )
53 simp12 1029 . . . . . . . . . . . 12  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  B  e.  NN )
5453nnred 8945 . . . . . . . . . . 11  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  B  e.  RR )
5554, 43ltaddposd 8499 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
0  <  B  <->  C  <  ( C  +  B ) ) )
5652, 55mpbid 147 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  C  <  ( C  +  B
) )
5741, 43, 45, 49, 56lttrd 8096 . . . . . . . 8  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( C  -  B )  <  ( C  +  B
) )
58 pythagtriplem10 12282 . . . . . . . . . . 11  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 ) )  ->  0  <  ( C  -  B )
)
59583adant3 1018 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  0  <  ( C  -  B
) )
60 0re 7970 . . . . . . . . . . 11  |-  0  e.  RR
61 ltle 8058 . . . . . . . . . . 11  |-  ( ( 0  e.  RR  /\  ( C  -  B
)  e.  RR )  ->  ( 0  < 
( C  -  B
)  ->  0  <_  ( C  -  B ) ) )
6260, 61mpan 424 . . . . . . . . . 10  |-  ( ( C  -  B )  e.  RR  ->  (
0  <  ( C  -  B )  ->  0  <_  ( C  -  B
) ) )
6341, 59, 62sylc 62 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  0  <_  ( C  -  B
) )
64 nngt0 8957 . . . . . . . . . . . . 13  |-  ( C  e.  NN  ->  0  <  C )
65643ad2ant3 1021 . . . . . . . . . . . 12  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  0  <  C )
66653ad2ant1 1019 . . . . . . . . . . 11  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  0  <  C )
6743, 54, 66, 52addgt0d 8491 . . . . . . . . . 10  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  0  <  ( C  +  B
) )
68 ltle 8058 . . . . . . . . . . 11  |-  ( ( 0  e.  RR  /\  ( C  +  B
)  e.  RR )  ->  ( 0  < 
( C  +  B
)  ->  0  <_  ( C  +  B ) ) )
6960, 68mpan 424 . . . . . . . . . 10  |-  ( ( C  +  B )  e.  RR  ->  (
0  <  ( C  +  B )  ->  0  <_  ( C  +  B
) ) )
7045, 67, 69sylc 62 . . . . . . . . 9  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  0  <_  ( C  +  B
) )
7141, 63, 45, 70sqrtltd 11194 . . . . . . . 8  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( C  -  B
)  <  ( C  +  B )  <->  ( sqr `  ( C  -  B
) )  <  ( sqr `  ( C  +  B ) ) ) )
7257, 71mpbid 147 . . . . . . 7  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  ( sqr `  ( C  -  B ) )  < 
( sqr `  ( C  +  B )
) )
73 nnsub 8971 . . . . . . . 8  |-  ( ( ( sqr `  ( C  -  B )
)  e.  NN  /\  ( sqr `  ( C  +  B ) )  e.  NN )  -> 
( ( sqr `  ( C  -  B )
)  <  ( sqr `  ( C  +  B
) )  <->  ( ( sqr `  ( C  +  B ) )  -  ( sqr `  ( C  -  B ) ) )  e.  NN ) )
7422, 2, 73syl2anc 411 . . . . . . 7  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( sqr `  ( C  -  B )
)  <  ( sqr `  ( C  +  B
) )  <->  ( ( sqr `  ( C  +  B ) )  -  ( sqr `  ( C  -  B ) ) )  e.  NN ) )
7572, 74mpbid 147 . . . . . 6  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  e.  NN )
7675nnzd 9387 . . . . 5  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  e.  ZZ )
77 evend2 11907 . . . . 5  |-  ( ( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  e.  ZZ  ->  ( 2 
||  ( ( sqr `  ( C  +  B
) )  -  ( sqr `  ( C  -  B ) ) )  <-> 
( ( ( sqr `  ( C  +  B
) )  -  ( sqr `  ( C  -  B ) ) )  /  2 )  e.  ZZ ) )
7876, 77syl 14 . . . 4  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
2  ||  ( ( sqr `  ( C  +  B ) )  -  ( sqr `  ( C  -  B ) ) )  <->  ( ( ( sqr `  ( C  +  B ) )  -  ( sqr `  ( C  -  B )
) )  /  2
)  e.  ZZ ) )
7939, 78mpbid 147 . . 3  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  / 
2 )  e.  ZZ )
8075nngt0d 8976 . . . 4  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  0  <  ( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) ) )
8175nnred 8945 . . . . 5  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  e.  RR )
82 halfpos2 9162 . . . . 5  |-  ( ( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  e.  RR  ->  ( 0  <  ( ( sqr `  ( C  +  B
) )  -  ( sqr `  ( C  -  B ) ) )  <->  0  <  ( ( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  / 
2 ) ) )
8381, 82syl 14 . . . 4  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
0  <  ( ( sqr `  ( C  +  B ) )  -  ( sqr `  ( C  -  B ) ) )  <->  0  <  (
( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  / 
2 ) ) )
8480, 83mpbid 147 . . 3  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  0  <  ( ( ( sqr `  ( C  +  B
) )  -  ( sqr `  ( C  -  B ) ) )  /  2 ) )
85 elnnz 9276 . . 3  |-  ( ( ( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  / 
2 )  e.  NN  <->  ( ( ( ( sqr `  ( C  +  B
) )  -  ( sqr `  ( C  -  B ) ) )  /  2 )  e.  ZZ  /\  0  < 
( ( ( sqr `  ( C  +  B
) )  -  ( sqr `  ( C  -  B ) ) )  /  2 ) ) )
8679, 84, 85sylanbrc 417 . 2  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  (
( ( sqr `  ( C  +  B )
)  -  ( sqr `  ( C  -  B
) ) )  / 
2 )  e.  NN )
871, 86eqeltrid 2274 1  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 )  /\  ( ( A  gcd  B )  =  1  /\ 
-.  2  ||  A
) )  ->  N  e.  NN )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    /\ wa 104    <-> wb 105    /\ w3a 979    = wceq 1363    e. wcel 2158   class class class wbr 4015   ` cfv 5228  (class class class)co 5888   RRcr 7823   0cc0 7824   1c1 7825    + caddc 7827    < clt 8005    <_ cle 8006    - cmin 8141    / cdiv 8642   NNcn 8932   2c2 8983   ZZcz 9266   RR+crp 9666   ^cexp 10532   sqrcsqrt 11018    || cdvds 11807    gcd cgcd 11956
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 615  ax-in2 616  ax-io 710  ax-5 1457  ax-7 1458  ax-gen 1459  ax-ie1 1503  ax-ie2 1504  ax-8 1514  ax-10 1515  ax-11 1516  ax-i12 1517  ax-bndl 1519  ax-4 1520  ax-17 1536  ax-i9 1540  ax-ial 1544  ax-i5r 1545  ax-13 2160  ax-14 2161  ax-ext 2169  ax-coll 4130  ax-sep 4133  ax-nul 4141  ax-pow 4186  ax-pr 4221  ax-un 4445  ax-setind 4548  ax-iinf 4599  ax-cnex 7915  ax-resscn 7916  ax-1cn 7917  ax-1re 7918  ax-icn 7919  ax-addcl 7920  ax-addrcl 7921  ax-mulcl 7922  ax-mulrcl 7923  ax-addcom 7924  ax-mulcom 7925  ax-addass 7926  ax-mulass 7927  ax-distr 7928  ax-i2m1 7929  ax-0lt1 7930  ax-1rid 7931  ax-0id 7932  ax-rnegex 7933  ax-precex 7934  ax-cnre 7935  ax-pre-ltirr 7936  ax-pre-ltwlin 7937  ax-pre-lttrn 7938  ax-pre-apti 7939  ax-pre-ltadd 7940  ax-pre-mulgt0 7941  ax-pre-mulext 7942  ax-arch 7943  ax-caucvg 7944
This theorem depends on definitions:  df-bi 117  df-stab 832  df-dc 836  df-3or 980  df-3an 981  df-tru 1366  df-fal 1369  df-xor 1386  df-nf 1471  df-sb 1773  df-eu 2039  df-mo 2040  df-clab 2174  df-cleq 2180  df-clel 2183  df-nfc 2318  df-ne 2358  df-nel 2453  df-ral 2470  df-rex 2471  df-reu 2472  df-rmo 2473  df-rab 2474  df-v 2751  df-sbc 2975  df-csb 3070  df-dif 3143  df-un 3145  df-in 3147  df-ss 3154  df-nul 3435  df-if 3547  df-pw 3589  df-sn 3610  df-pr 3611  df-op 3613  df-uni 3822  df-int 3857  df-iun 3900  df-br 4016  df-opab 4077  df-mpt 4078  df-tr 4114  df-id 4305  df-po 4308  df-iso 4309  df-iord 4378  df-on 4380  df-ilim 4381  df-suc 4383  df-iom 4602  df-xp 4644  df-rel 4645  df-cnv 4646  df-co 4647  df-dm 4648  df-rn 4649  df-res 4650  df-ima 4651  df-iota 5190  df-fun 5230  df-fn 5231  df-f 5232  df-f1 5233  df-fo 5234  df-f1o 5235  df-fv 5236  df-riota 5844  df-ov 5891  df-oprab 5892  df-mpo 5893  df-1st 6154  df-2nd 6155  df-recs 6319  df-frec 6405  df-1o 6430  df-2o 6431  df-er 6548  df-en 6754  df-sup 6996  df-pnf 8007  df-mnf 8008  df-xr 8009  df-ltxr 8010  df-le 8011  df-sub 8143  df-neg 8144  df-reap 8545  df-ap 8552  df-div 8643  df-inn 8933  df-2 8991  df-3 8992  df-4 8993  df-n0 9190  df-z 9267  df-uz 9542  df-q 9633  df-rp 9667  df-fz 10022  df-fzo 10156  df-fl 10283  df-mod 10336  df-seqfrec 10459  df-exp 10533  df-cj 10864  df-re 10865  df-im 10866  df-rsqrt 11020  df-abs 11021  df-dvds 11808  df-gcd 11957  df-prm 12121
This theorem is referenced by:  pythagtriplem18  12294
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