Theorem coscld

Description: Closure of the cosine function. (Contributed by Mario Carneiro, 29-May-2016)

	Ref	Expression
Hypothesis	sincld.1	$$⊢\phi \to A\in ℂ$$
Assertion	coscld	$$⊢\phi \to \cos A\in ℂ$$

Proof

Step	Hyp	Ref	Expression
1		sincld.1	$$⊢\phi \to A\in ℂ$$
2		coscl	$$⊢A\in ℂ\to \cos A\in ℂ$$
3	1 2	syl	$$⊢\phi \to \cos A\in ℂ$$