Theorem coscld

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

	Ref	Expression
Hypothesis	sincld.1	|- ( ph -> A e. CC )
Assertion	coscld	|- ( ph -> ( cos ` A ) e. CC )

Proof

Step	Hyp	Ref	Expression
1		sincld.1	|- ( ph -> A e. CC )
2		coscl	|- ( A e. CC -> ( cos ` A ) e. CC )
3	1 2	syl	|- ( ph -> ( cos ` A ) e. CC )