Theorem readd

Description: Real part distributes over addition. (Contributed by NM, 17-Mar-2005) (Revised by Mario Carneiro, 14-Jul-2014)

	Ref	Expression
Assertion	readd	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℜ ‘ ( 𝐴 + 𝐵 ) ) = ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) )

Proof

Step	Hyp	Ref	Expression
1		recl	⊢ ( 𝐴 ∈ ℂ → ( ℜ ‘ 𝐴 ) ∈ ℝ )
2	1	adantr	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℜ ‘ 𝐴 ) ∈ ℝ )
3	2	recnd	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℜ ‘ 𝐴 ) ∈ ℂ )
4		ax-icn	⊢ i ∈ ℂ
5		imcl	⊢ ( 𝐴 ∈ ℂ → ( ℑ ‘ 𝐴 ) ∈ ℝ )
6	5	adantr	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℑ ‘ 𝐴 ) ∈ ℝ )
7	6	recnd	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℑ ‘ 𝐴 ) ∈ ℂ )
8		mulcl	⊢ ( ( i ∈ ℂ ∧ ( ℑ ‘ 𝐴 ) ∈ ℂ ) → ( i · ( ℑ ‘ 𝐴 ) ) ∈ ℂ )
9	4 7 8	sylancr	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( i · ( ℑ ‘ 𝐴 ) ) ∈ ℂ )
10		recl	⊢ ( 𝐵 ∈ ℂ → ( ℜ ‘ 𝐵 ) ∈ ℝ )
11	10	adantl	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℜ ‘ 𝐵 ) ∈ ℝ )
12	11	recnd	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℜ ‘ 𝐵 ) ∈ ℂ )
13		imcl	⊢ ( 𝐵 ∈ ℂ → ( ℑ ‘ 𝐵 ) ∈ ℝ )
14	13	adantl	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℑ ‘ 𝐵 ) ∈ ℝ )
15	14	recnd	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℑ ‘ 𝐵 ) ∈ ℂ )
16		mulcl	⊢ ( ( i ∈ ℂ ∧ ( ℑ ‘ 𝐵 ) ∈ ℂ ) → ( i · ( ℑ ‘ 𝐵 ) ) ∈ ℂ )
17	4 15 16	sylancr	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( i · ( ℑ ‘ 𝐵 ) ) ∈ ℂ )
18	3 9 12 17	add4d	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ( ( ℜ ‘ 𝐴 ) + ( i · ( ℑ ‘ 𝐴 ) ) ) + ( ( ℜ ‘ 𝐵 ) + ( i · ( ℑ ‘ 𝐵 ) ) ) ) = ( ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) + ( ( i · ( ℑ ‘ 𝐴 ) ) + ( i · ( ℑ ‘ 𝐵 ) ) ) ) )
19		replim	⊢ ( 𝐴 ∈ ℂ → 𝐴 = ( ( ℜ ‘ 𝐴 ) + ( i · ( ℑ ‘ 𝐴 ) ) ) )
20		replim	⊢ ( 𝐵 ∈ ℂ → 𝐵 = ( ( ℜ ‘ 𝐵 ) + ( i · ( ℑ ‘ 𝐵 ) ) ) )
21	19 20	oveqan12d	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( 𝐴 + 𝐵 ) = ( ( ( ℜ ‘ 𝐴 ) + ( i · ( ℑ ‘ 𝐴 ) ) ) + ( ( ℜ ‘ 𝐵 ) + ( i · ( ℑ ‘ 𝐵 ) ) ) ) )
22	4	a1i	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → i ∈ ℂ )
23	22 7 15	adddid	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( i · ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ) = ( ( i · ( ℑ ‘ 𝐴 ) ) + ( i · ( ℑ ‘ 𝐵 ) ) ) )
24	23	oveq2d	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) + ( i · ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ) ) = ( ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) + ( ( i · ( ℑ ‘ 𝐴 ) ) + ( i · ( ℑ ‘ 𝐵 ) ) ) ) )
25	18 21 24	3eqtr4d	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( 𝐴 + 𝐵 ) = ( ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) + ( i · ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ) ) )
26	25	fveq2d	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℜ ‘ ( 𝐴 + 𝐵 ) ) = ( ℜ ‘ ( ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) + ( i · ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ) ) ) )
27		readdcl	⊢ ( ( ( ℜ ‘ 𝐴 ) ∈ ℝ ∧ ( ℜ ‘ 𝐵 ) ∈ ℝ ) → ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) ∈ ℝ )
28	1 10 27	syl2an	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) ∈ ℝ )
29		readdcl	⊢ ( ( ( ℑ ‘ 𝐴 ) ∈ ℝ ∧ ( ℑ ‘ 𝐵 ) ∈ ℝ ) → ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ∈ ℝ )
30	5 13 29	syl2an	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ∈ ℝ )
31		crre	⊢ ( ( ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) ∈ ℝ ∧ ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ∈ ℝ ) → ( ℜ ‘ ( ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) + ( i · ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ) ) ) = ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) )
32	28 30 31	syl2anc	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℜ ‘ ( ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) + ( i · ( ( ℑ ‘ 𝐴 ) + ( ℑ ‘ 𝐵 ) ) ) ) ) = ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) )
33	26 32	eqtrd	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ℜ ‘ ( 𝐴 + 𝐵 ) ) = ( ( ℜ ‘ 𝐴 ) + ( ℜ ‘ 𝐵 ) ) )