Proof of Theorem pythagtriplem11
| Step | Hyp | Ref
 | Expression | 
| 1 |   | pythagtriplem11.1 | 
. 2
⊢ 𝑀 = (((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2) | 
| 2 |   | pythagtriplem9 12442 | 
. . . . . 6
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (√‘(𝐶 + 𝐵)) ∈ ℕ) | 
| 3 | 2 | nnzd 9447 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (√‘(𝐶 + 𝐵)) ∈ ℤ) | 
| 4 |   | simp3r 1028 | 
. . . . . . 7
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ¬ 2 ∥ 𝐴) | 
| 5 |   | 2z 9354 | 
. . . . . . . . . 10
⊢ 2 ∈
ℤ | 
| 6 |   | nnz 9345 | 
. . . . . . . . . . . . 13
⊢ (𝐶 ∈ ℕ → 𝐶 ∈
ℤ) | 
| 7 | 6 | 3ad2ant3 1022 | 
. . . . . . . . . . . 12
⊢ ((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) → 𝐶 ∈
ℤ) | 
| 8 |   | nnz 9345 | 
. . . . . . . . . . . . 13
⊢ (𝐵 ∈ ℕ → 𝐵 ∈
ℤ) | 
| 9 | 8 | 3ad2ant2 1021 | 
. . . . . . . . . . . 12
⊢ ((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) → 𝐵 ∈
ℤ) | 
| 10 | 7, 9 | zaddcld 9452 | 
. . . . . . . . . . 11
⊢ ((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) → (𝐶 + 𝐵) ∈ ℤ) | 
| 11 | 10 | 3ad2ant1 1020 | 
. . . . . . . . . 10
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (𝐶 + 𝐵) ∈ ℤ) | 
| 12 |   | nnz 9345 | 
. . . . . . . . . . . 12
⊢ (𝐴 ∈ ℕ → 𝐴 ∈
ℤ) | 
| 13 | 12 | 3ad2ant1 1020 | 
. . . . . . . . . . 11
⊢ ((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) → 𝐴 ∈
ℤ) | 
| 14 | 13 | 3ad2ant1 1020 | 
. . . . . . . . . 10
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → 𝐴 ∈ ℤ) | 
| 15 |   | dvdsgcdb 12180 | 
. . . . . . . . . 10
⊢ ((2
∈ ℤ ∧ (𝐶 +
𝐵) ∈ ℤ ∧
𝐴 ∈ ℤ) →
((2 ∥ (𝐶 + 𝐵) ∧ 2 ∥ 𝐴) ↔ 2 ∥ ((𝐶 + 𝐵) gcd 𝐴))) | 
| 16 | 5, 11, 14, 15 | mp3an2i 1353 | 
. . . . . . . . 9
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ((2 ∥ (𝐶 + 𝐵) ∧ 2 ∥ 𝐴) ↔ 2 ∥ ((𝐶 + 𝐵) gcd 𝐴))) | 
| 17 | 16 | biimpar 297 | 
. . . . . . . 8
⊢ ((((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) ∧ 2 ∥ ((𝐶 + 𝐵) gcd 𝐴)) → (2 ∥ (𝐶 + 𝐵) ∧ 2 ∥ 𝐴)) | 
| 18 | 17 | simprd 114 | 
. . . . . . 7
⊢ ((((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) ∧ 2 ∥ ((𝐶 + 𝐵) gcd 𝐴)) → 2 ∥ 𝐴) | 
| 19 | 4, 18 | mtand 666 | 
. . . . . 6
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ¬ 2 ∥
((𝐶 + 𝐵) gcd 𝐴)) | 
| 20 |   | pythagtriplem7 12440 | 
. . . . . . 7
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (√‘(𝐶 + 𝐵)) = ((𝐶 + 𝐵) gcd 𝐴)) | 
| 21 | 20 | breq2d 4045 | 
. . . . . 6
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (2 ∥
(√‘(𝐶 + 𝐵)) ↔ 2 ∥ ((𝐶 + 𝐵) gcd 𝐴))) | 
| 22 | 19, 21 | mtbird 674 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ¬ 2 ∥
(√‘(𝐶 + 𝐵))) | 
| 23 |   | pythagtriplem8 12441 | 
. . . . . 6
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (√‘(𝐶 − 𝐵)) ∈ ℕ) | 
| 24 | 23 | nnzd 9447 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (√‘(𝐶 − 𝐵)) ∈ ℤ) | 
| 25 | 7, 9 | zsubcld 9453 | 
. . . . . . . . . . 11
⊢ ((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) → (𝐶 − 𝐵) ∈ ℤ) | 
| 26 | 25 | 3ad2ant1 1020 | 
. . . . . . . . . 10
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (𝐶 − 𝐵) ∈ ℤ) | 
| 27 |   | dvdsgcdb 12180 | 
. . . . . . . . . 10
⊢ ((2
∈ ℤ ∧ (𝐶
− 𝐵) ∈ ℤ
∧ 𝐴 ∈ ℤ)
→ ((2 ∥ (𝐶
− 𝐵) ∧ 2 ∥
𝐴) ↔ 2 ∥ ((𝐶 − 𝐵) gcd 𝐴))) | 
| 28 | 5, 26, 14, 27 | mp3an2i 1353 | 
. . . . . . . . 9
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ((2 ∥ (𝐶 − 𝐵) ∧ 2 ∥ 𝐴) ↔ 2 ∥ ((𝐶 − 𝐵) gcd 𝐴))) | 
| 29 | 28 | biimpar 297 | 
. . . . . . . 8
⊢ ((((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) ∧ 2 ∥ ((𝐶 − 𝐵) gcd 𝐴)) → (2 ∥ (𝐶 − 𝐵) ∧ 2 ∥ 𝐴)) | 
| 30 | 29 | simprd 114 | 
. . . . . . 7
⊢ ((((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) ∧ 2 ∥ ((𝐶 − 𝐵) gcd 𝐴)) → 2 ∥ 𝐴) | 
| 31 | 4, 30 | mtand 666 | 
. . . . . 6
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ¬ 2 ∥
((𝐶 − 𝐵) gcd 𝐴)) | 
| 32 |   | pythagtriplem6 12439 | 
. . . . . . 7
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (√‘(𝐶 − 𝐵)) = ((𝐶 − 𝐵) gcd 𝐴)) | 
| 33 | 32 | breq2d 4045 | 
. . . . . 6
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (2 ∥
(√‘(𝐶 −
𝐵)) ↔ 2 ∥
((𝐶 − 𝐵) gcd 𝐴))) | 
| 34 | 31, 33 | mtbird 674 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ¬ 2 ∥
(√‘(𝐶 −
𝐵))) | 
| 35 |   | opoe 12060 | 
. . . . 5
⊢
((((√‘(𝐶
+ 𝐵)) ∈ ℤ ∧
¬ 2 ∥ (√‘(𝐶 + 𝐵))) ∧ ((√‘(𝐶 − 𝐵)) ∈ ℤ ∧ ¬ 2 ∥
(√‘(𝐶 −
𝐵)))) → 2 ∥
((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵)))) | 
| 36 | 3, 22, 24, 34, 35 | syl22anc 1250 | 
. . . 4
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → 2 ∥
((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵)))) | 
| 37 | 2, 23 | nnaddcld 9038 | 
. . . . . 6
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) ∈ ℕ) | 
| 38 | 37 | nnzd 9447 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) ∈ ℤ) | 
| 39 |   | evend2 12054 | 
. . . . 5
⊢
(((√‘(𝐶
+ 𝐵)) +
(√‘(𝐶 −
𝐵))) ∈ ℤ →
(2 ∥ ((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) ↔ (((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2) ∈ ℤ)) | 
| 40 | 38, 39 | syl 14 | 
. . . 4
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (2 ∥
((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) ↔ (((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2) ∈ ℤ)) | 
| 41 | 36, 40 | mpbid 147 | 
. . 3
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) →
(((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2) ∈ ℤ) | 
| 42 | 2 | nnred 9003 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (√‘(𝐶 + 𝐵)) ∈ ℝ) | 
| 43 | 23 | nnred 9003 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (√‘(𝐶 − 𝐵)) ∈ ℝ) | 
| 44 | 2 | nngt0d 9034 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → 0 <
(√‘(𝐶 + 𝐵))) | 
| 45 | 23 | nngt0d 9034 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → 0 <
(√‘(𝐶 −
𝐵))) | 
| 46 | 42, 43, 44, 45 | addgt0d 8548 | 
. . . 4
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → 0 <
((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵)))) | 
| 47 | 37 | nnred 9003 | 
. . . . 5
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → ((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) ∈ ℝ) | 
| 48 |   | halfpos2 9221 | 
. . . . 5
⊢
(((√‘(𝐶
+ 𝐵)) +
(√‘(𝐶 −
𝐵))) ∈ ℝ →
(0 < ((√‘(𝐶
+ 𝐵)) +
(√‘(𝐶 −
𝐵))) ↔ 0 <
(((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2))) | 
| 49 | 47, 48 | syl 14 | 
. . . 4
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → (0 <
((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) ↔ 0 < (((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2))) | 
| 50 | 46, 49 | mpbid 147 | 
. . 3
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → 0 <
(((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2)) | 
| 51 |   | elnnz 9336 | 
. . 3
⊢
((((√‘(𝐶
+ 𝐵)) +
(√‘(𝐶 −
𝐵))) / 2) ∈ ℕ
↔ ((((√‘(𝐶
+ 𝐵)) +
(√‘(𝐶 −
𝐵))) / 2) ∈ ℤ
∧ 0 < (((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2))) | 
| 52 | 41, 50, 51 | sylanbrc 417 | 
. 2
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) →
(((√‘(𝐶 + 𝐵)) + (√‘(𝐶 − 𝐵))) / 2) ∈ ℕ) | 
| 53 | 1, 52 | eqeltrid 2283 | 
1
⊢ (((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ) ∧ ((𝐴↑2) + (𝐵↑2)) = (𝐶↑2) ∧ ((𝐴 gcd 𝐵) = 1 ∧ ¬ 2 ∥ 𝐴)) → 𝑀 ∈ ℕ) |