Theorem uneq1d

Description: Deduction adding union to the right in a class equality. (Contributed by NM, 29-Mar-1998)

	Ref	Expression
Hypothesis	uneq1d.1	$$⊢\phi \to A=B$$
Assertion	uneq1d	$$⊢\phi \to A\cup C=B\cup C$$

Proof

Step	Hyp	Ref	Expression
1		uneq1d.1	$$⊢\phi \to A=B$$
2		uneq1	$$⊢A=B\to A\cup C=B\cup C$$
3	1 2	syl	$$⊢\phi \to A\cup C=B\cup C$$