Theorem coideq

Description: Equality theorem for composition of two classes. (Contributed by Peter Mazsa, 23-Sep-2021)

	Ref	Expression
Assertion	coideq	$$⊢A=B\to A\circ A=B\circ B$$

Proof

Step	Hyp	Ref	Expression
1		coeq1	$$⊢A=B\to A\circ A=B\circ A$$
2		coeq2	$$⊢A=B\to B\circ A=B\circ B$$
3	1 2	eqtrd	$$⊢A=B\to A\circ A=B\circ B$$