Theorem divelunit

Description: A condition for a ratio to be a member of the closed unit interval. (Contributed by Scott Fenton, 11-Jun-2013)

	Ref	Expression
Assertion	divelunit	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( ( 𝐴 / 𝐵 ) ∈ ( 0 [,] 1 ) ↔ 𝐴 ≤ 𝐵 ) )

Proof

Step	Hyp	Ref	Expression
1		elicc01	⊢ ( ( 𝐴 / 𝐵 ) ∈ ( 0 [,] 1 ) ↔ ( ( 𝐴 / 𝐵 ) ∈ ℝ ∧ 0 ≤ ( 𝐴 / 𝐵 ) ∧ ( 𝐴 / 𝐵 ) ≤ 1 ) )
2		df-3an	⊢ ( ( ( 𝐴 / 𝐵 ) ∈ ℝ ∧ 0 ≤ ( 𝐴 / 𝐵 ) ∧ ( 𝐴 / 𝐵 ) ≤ 1 ) ↔ ( ( ( 𝐴 / 𝐵 ) ∈ ℝ ∧ 0 ≤ ( 𝐴 / 𝐵 ) ) ∧ ( 𝐴 / 𝐵 ) ≤ 1 ) )
3	1 2	bitri	⊢ ( ( 𝐴 / 𝐵 ) ∈ ( 0 [,] 1 ) ↔ ( ( ( 𝐴 / 𝐵 ) ∈ ℝ ∧ 0 ≤ ( 𝐴 / 𝐵 ) ) ∧ ( 𝐴 / 𝐵 ) ≤ 1 ) )
4		1re	⊢ 1 ∈ ℝ
5		ledivmul	⊢ ( ( 𝐴 ∈ ℝ ∧ 1 ∈ ℝ ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( ( 𝐴 / 𝐵 ) ≤ 1 ↔ 𝐴 ≤ ( 𝐵 · 1 ) ) )
6	4 5	mp3an2	⊢ ( ( 𝐴 ∈ ℝ ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( ( 𝐴 / 𝐵 ) ≤ 1 ↔ 𝐴 ≤ ( 𝐵 · 1 ) ) )
7	6	adantlr	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( ( 𝐴 / 𝐵 ) ≤ 1 ↔ 𝐴 ≤ ( 𝐵 · 1 ) ) )
8		simpll	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → 𝐴 ∈ ℝ )
9		simprl	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → 𝐵 ∈ ℝ )
10		gt0ne0	⊢ ( ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) → 𝐵 ≠ 0 )
11	10	adantl	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → 𝐵 ≠ 0 )
12	8 9 11	redivcld	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( 𝐴 / 𝐵 ) ∈ ℝ )
13		divge0	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → 0 ≤ ( 𝐴 / 𝐵 ) )
14	12 13	jca	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( ( 𝐴 / 𝐵 ) ∈ ℝ ∧ 0 ≤ ( 𝐴 / 𝐵 ) ) )
15	14	biantrurd	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( ( 𝐴 / 𝐵 ) ≤ 1 ↔ ( ( ( 𝐴 / 𝐵 ) ∈ ℝ ∧ 0 ≤ ( 𝐴 / 𝐵 ) ) ∧ ( 𝐴 / 𝐵 ) ≤ 1 ) ) )
16		recn	⊢ ( 𝐵 ∈ ℝ → 𝐵 ∈ ℂ )
17	16	ad2antrl	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → 𝐵 ∈ ℂ )
18	17	mulid1d	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( 𝐵 · 1 ) = 𝐵 )
19	18	breq2d	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( 𝐴 ≤ ( 𝐵 · 1 ) ↔ 𝐴 ≤ 𝐵 ) )
20	7 15 19	3bitr3d	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( ( ( ( 𝐴 / 𝐵 ) ∈ ℝ ∧ 0 ≤ ( 𝐴 / 𝐵 ) ) ∧ ( 𝐴 / 𝐵 ) ≤ 1 ) ↔ 𝐴 ≤ 𝐵 ) )
21	3 20	syl5bb	⊢ ( ( ( 𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ) ∧ ( 𝐵 ∈ ℝ ∧ 0 < 𝐵 ) ) → ( ( 𝐴 / 𝐵 ) ∈ ( 0 [,] 1 ) ↔ 𝐴 ≤ 𝐵 ) )