Theorem coscl

Description: Closure of the cosine function with a complex argument. (Contributed by NM, 28-Apr-2005) (Revised by Mario Carneiro, 30-Apr-2014)

	Ref	Expression
Assertion	coscl	$$⊢A\in ℂ\to \cos A\in ℂ$$

Proof

Step	Hyp	Ref	Expression
1		cosf	$$⊢\cos :ℂ⟶ℂ$$
2	1	ffvelrni	$$⊢A\in ℂ\to \cos A\in ℂ$$