Theorem cjmulrcld

Description: A complex number times its conjugate is real. (Contributed by Mario Carneiro, 29-May-2016)

	Ref	Expression
Hypothesis	recld.1	$$⊢\phi \to A\in ℂ$$
Assertion	cjmulrcld	$$⊢\phi \to A\bar{A}\in ℝ$$

Proof

Step	Hyp	Ref	Expression
1		recld.1	$$⊢\phi \to A\in ℂ$$
2		cjmulrcl	$$⊢A\in ℂ\to A\bar{A}\in ℝ$$
3	1 2	syl	$$⊢\phi \to A\bar{A}\in ℝ$$