Theorem bj-pr2eq

Description: Substitution property for pr2 . (Contributed by BJ, 6-Oct-2018)

	Ref	Expression
Assertion	bj-pr2eq	$$⊢A=B\to pr2A=pr2B$$

Proof

Step	Hyp	Ref	Expression
1		bj-projeq2	$$⊢A=B\to \left(1_{𝑜}ProjA\right)=\left(1_{𝑜}ProjB\right)$$
2		df-bj-pr2	$$⊢pr2A=\left(1_{𝑜}ProjA\right)$$
3		df-bj-pr2	$$⊢pr2B=\left(1_{𝑜}ProjB\right)$$
4	1 2 3	3eqtr4g	$$⊢A=B\to pr2A=pr2B$$