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Metamath Proof Explorer

Theorem pythagtriplem10

Description: Lemma for pythagtrip . Show that C - B is positive. (Contributed by Scott Fenton, 17-Apr-2014) (Revised by Mario Carneiro, 19-Apr-2014)

Ref Expression
Assertion pythagtriplem10 ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → 0 < ( 𝐶 − 𝐵 ) )

Proof

Step Hyp Ref Expression
1 nnre ⊢ ( 𝐴 ∈ ℕ → 𝐴 ∈ ℝ )
2 1 3ad2ant1 ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → 𝐴 ∈ ℝ )
3 nnne0 ⊢ ( 𝐴 ∈ ℕ → 𝐴 ≠ 0 )
4 3 3ad2ant1 ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → 𝐴 ≠ 0 )
5 2 4 sqgt0d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → 0 < ( 𝐴 ↑ 2 ) )
6 2 resqcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → ( 𝐴 ↑ 2 ) ∈ ℝ )
7 nnre ⊢ ( 𝐵 ∈ ℕ → 𝐵 ∈ ℝ )
8 7 3ad2ant2 ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → 𝐵 ∈ ℝ )
9 8 resqcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → ( 𝐵 ↑ 2 ) ∈ ℝ )
10 6 9 ltaddpos2d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → ( 0 < ( 𝐴 ↑ 2 ) ↔ ( 𝐵 ↑ 2 ) < ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) ) )
11 5 10 mpbid ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → ( 𝐵 ↑ 2 ) < ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) )
12 11 adantr ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → ( 𝐵 ↑ 2 ) < ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) )
13 simpr ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) )
14 12 13 breqtrd ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → ( 𝐵 ↑ 2 ) < ( 𝐶 ↑ 2 ) )
15 8 adantr ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → 𝐵 ∈ ℝ )
16 nnre ⊢ ( 𝐶 ∈ ℕ → 𝐶 ∈ ℝ )
17 16 3ad2ant3 ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → 𝐶 ∈ ℝ )
18 17 adantr ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → 𝐶 ∈ ℝ )
19 nnnn0 ⊢ ( 𝐵 ∈ ℕ → 𝐵 ∈ ℕ0 )
20 19 nn0ge0d ⊢ ( 𝐵 ∈ ℕ → 0 ≤ 𝐵 )
21 20 3ad2ant2 ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → 0 ≤ 𝐵 )
22 21 adantr ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → 0 ≤ 𝐵 )
23 nnnn0 ⊢ ( 𝐶 ∈ ℕ → 𝐶 ∈ ℕ0 )
24 23 nn0ge0d ⊢ ( 𝐶 ∈ ℕ → 0 ≤ 𝐶 )
25 24 3ad2ant3 ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) → 0 ≤ 𝐶 )
26 25 adantr ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → 0 ≤ 𝐶 )
27 15 18 22 26 lt2sqd ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → ( 𝐵 < 𝐶 ↔ ( 𝐵 ↑ 2 ) < ( 𝐶 ↑ 2 ) ) )
28 14 27 mpbird ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → 𝐵 < 𝐶 )
29 15 18 posdifd ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → ( 𝐵 < 𝐶 ↔ 0 < ( 𝐶 − 𝐵 ) ) )
30 28 29 mpbid ⊢ ( ( ( 𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐶 ∈ ℕ ) ∧ ( ( 𝐴 ↑ 2 ) + ( 𝐵 ↑ 2 ) ) = ( 𝐶 ↑ 2 ) ) → 0 < ( 𝐶 − 𝐵 ) )