Theorem 3eqtr3ri 2207

Description: An inference from three chained equalities. (Contributed by NM, 15-Aug-2004.)

Hypotheses

Ref	Expression
3eqtr3i.1	|- A = B
3eqtr3i.2	|- A = C
3eqtr3i.3	|- B = D

Assertion

Ref	Expression
3eqtr3ri	|- D = C

Proof of Theorem 3eqtr3ri

Step	Hyp	Ref	Expression
1		3eqtr3i.3	. 2 |- B = D
2		3eqtr3i.1	. . 3 |- A = B
3		3eqtr3i.2	. . 3 |- A = C
4	2, 3	eqtr3i 2200	. 2 |- B = C
5	1, 4	eqtr3i 2200	1 |- D = C

Syntax hints:   = wceq 1353

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1447  ax-gen 1449  ax-4 1510  ax-17 1526  ax-ext 2159

This theorem depends on definitions:  df-bi 117  df-cleq 2170

This theorem is referenced by:  indif2  3379  resdm2  5116  co01  5140  cocnvres  5150  undifdc  6918  1mhlfehlf  9131  rei  10899  resqrexlemover  11010  cos1bnd  11758  6gcd4e2  11986  3lcm2e6  12150  cosq23lt0  14036  sincos4thpi  14043  sincos6thpi  14045  cosq34lt1  14053