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Theorem pythagtriplem13 12785
Description: Lemma for pythagtrip 12792. 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 12782 . . . . . 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 9556 . . . . 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 1050 . . . . . . 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 9462 . . . . . . . . . 10  |-  2  e.  ZZ
6 simp3 1023 . . . . . . . . . . . . 13  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  C  e.  NN )
7 simp2 1022 . . . . . . . . . . . . 13  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  B  e.  NN )
86, 7nnaddcld 9146 . . . . . . . . . . . 12  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  +  B )  e.  NN )
98nnzd 9556 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  +  B )  e.  ZZ )
1093ad2ant1 1042 . . . . . . . . . 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 9453 . . . . . . . . . . . 12  |-  ( A  e.  NN  ->  A  e.  ZZ )
12113ad2ant1 1042 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  A  e.  ZZ )
13123ad2ant1 1042 . . . . . . . . . 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 12520 . . . . . . . . . 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 1376 . . . . . . . . 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 669 . . . . . 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 12780 . . . . . . 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 4094 . . . . . 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 677 . . . . 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 12781 . . . . . 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 9556 . . . . 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 9453 . . . . . . . . . . . . 13  |-  ( C  e.  NN  ->  C  e.  ZZ )
25243ad2ant3 1044 . . . . . . . . . . . 12  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  C  e.  ZZ )
26 nnz 9453 . . . . . . . . . . . . 13  |-  ( B  e.  NN  ->  B  e.  ZZ )
27263ad2ant2 1043 . . . . . . . . . . . 12  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  B  e.  ZZ )
2825, 27zsubcld 9562 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  -  B )  e.  ZZ )
29283ad2ant1 1042 . . . . . . . . . 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 12520 . . . . . . . . . 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 1376 . . . . . . . . 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 669 . . . . . 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 12779 . . . . . . 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 4094 . . . . . 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 677 . . . . 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 12393 . . . . 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 1272 . . . 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 9557 . . . . . . . . . 10  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  -  B )  e.  RR )
41403ad2ant1 1042 . . . . . . . . 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 1053 . . . . . . . . . 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 9111 . . . . . . . . 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 9111 . . . . . . . . . 10  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  ( C  +  B )  e.  RR )
45443ad2ant1 1042 . . . . . . . . 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 9847 . . . . . . . . . . . 12  |-  ( B  e.  NN  ->  B  e.  RR+ )
47463ad2ant2 1043 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  B  e.  RR+ )
48473ad2ant1 1042 . . . . . . . . . 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 9913 . . . . . . . . 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 9123 . . . . . . . . . . . 12  |-  ( B  e.  NN  ->  0  <  B )
51503ad2ant2 1043 . . . . . . . . . . 11  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  0  <  B )
52513ad2ant1 1042 . . . . . . . . . 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 1052 . . . . . . . . . . . 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 9111 . . . . . . . . . . 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 8664 . . . . . . . . . 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 8260 . . . . . . . 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 12778 . . . . . . . . . . 11  |-  ( ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  /\  ( ( A ^
2 )  +  ( B ^ 2 ) )  =  ( C ^ 2 ) )  ->  0  <  ( C  -  B )
)
59583adant3 1041 . . . . . . . . . 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 8134 . . . . . . . . . . 11  |-  0  e.  RR
61 ltle 8222 . . . . . . . . . . 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 9123 . . . . . . . . . . . . 13  |-  ( C  e.  NN  ->  0  <  C )
65643ad2ant3 1044 . . . . . . . . . . . 12  |-  ( ( A  e.  NN  /\  B  e.  NN  /\  C  e.  NN )  ->  0  <  C )
66653ad2ant1 1042 . . . . . . . . . . 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 8656 . . . . . . . . . 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 8222 . . . . . . . . . . 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 11669 . . . . . . . 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 9137 . . . . . . . 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 9556 . . . . 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 12386 . . . . 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 9142 . . . 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 9111 . . . . 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 9329 . . . . 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 9444 . . 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 2316 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 1002    = wceq 1395    e. wcel 2200   class class class wbr 4082   ` cfv 5314  (class class class)co 5994   RRcr 7986   0cc0 7987   1c1 7988    + caddc 7990    < clt 8169    <_ cle 8170    - cmin 8305    / cdiv 8807   NNcn 9098   2c2 9149   ZZcz 9434   RR+crp 9837   ^cexp 10747   sqrcsqrt 11493    || cdvds 12284    gcd cgcd 12460
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 617  ax-in2 618  ax-io 714  ax-5 1493  ax-7 1494  ax-gen 1495  ax-ie1 1539  ax-ie2 1540  ax-8 1550  ax-10 1551  ax-11 1552  ax-i12 1553  ax-bndl 1555  ax-4 1556  ax-17 1572  ax-i9 1576  ax-ial 1580  ax-i5r 1581  ax-13 2202  ax-14 2203  ax-ext 2211  ax-coll 4198  ax-sep 4201  ax-nul 4209  ax-pow 4257  ax-pr 4292  ax-un 4521  ax-setind 4626  ax-iinf 4677  ax-cnex 8078  ax-resscn 8079  ax-1cn 8080  ax-1re 8081  ax-icn 8082  ax-addcl 8083  ax-addrcl 8084  ax-mulcl 8085  ax-mulrcl 8086  ax-addcom 8087  ax-mulcom 8088  ax-addass 8089  ax-mulass 8090  ax-distr 8091  ax-i2m1 8092  ax-0lt1 8093  ax-1rid 8094  ax-0id 8095  ax-rnegex 8096  ax-precex 8097  ax-cnre 8098  ax-pre-ltirr 8099  ax-pre-ltwlin 8100  ax-pre-lttrn 8101  ax-pre-apti 8102  ax-pre-ltadd 8103  ax-pre-mulgt0 8104  ax-pre-mulext 8105  ax-arch 8106  ax-caucvg 8107
This theorem depends on definitions:  df-bi 117  df-stab 836  df-dc 840  df-3or 1003  df-3an 1004  df-tru 1398  df-fal 1401  df-xor 1418  df-nf 1507  df-sb 1809  df-eu 2080  df-mo 2081  df-clab 2216  df-cleq 2222  df-clel 2225  df-nfc 2361  df-ne 2401  df-nel 2496  df-ral 2513  df-rex 2514  df-reu 2515  df-rmo 2516  df-rab 2517  df-v 2801  df-sbc 3029  df-csb 3125  df-dif 3199  df-un 3201  df-in 3203  df-ss 3210  df-nul 3492  df-if 3603  df-pw 3651  df-sn 3672  df-pr 3673  df-op 3675  df-uni 3888  df-int 3923  df-iun 3966  df-br 4083  df-opab 4145  df-mpt 4146  df-tr 4182  df-id 4381  df-po 4384  df-iso 4385  df-iord 4454  df-on 4456  df-ilim 4457  df-suc 4459  df-iom 4680  df-xp 4722  df-rel 4723  df-cnv 4724  df-co 4725  df-dm 4726  df-rn 4727  df-res 4728  df-ima 4729  df-iota 5274  df-fun 5316  df-fn 5317  df-f 5318  df-f1 5319  df-fo 5320  df-f1o 5321  df-fv 5322  df-riota 5947  df-ov 5997  df-oprab 5998  df-mpo 5999  df-1st 6276  df-2nd 6277  df-recs 6441  df-frec 6527  df-1o 6552  df-2o 6553  df-er 6670  df-en 6878  df-sup 7139  df-pnf 8171  df-mnf 8172  df-xr 8173  df-ltxr 8174  df-le 8175  df-sub 8307  df-neg 8308  df-reap 8710  df-ap 8717  df-div 8808  df-inn 9099  df-2 9157  df-3 9158  df-4 9159  df-n0 9358  df-z 9435  df-uz 9711  df-q 9803  df-rp 9838  df-fz 10193  df-fzo 10327  df-fl 10477  df-mod 10532  df-seqfrec 10657  df-exp 10748  df-cj 11339  df-re 11340  df-im 11341  df-rsqrt 11495  df-abs 11496  df-dvds 12285  df-gcd 12461  df-prm 12616
This theorem is referenced by:  pythagtriplem18  12790
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