The problem describes the transitive property of triangle congruence. Given that triangle $ABC$ is congruent to triangle $DEF$ and triangle $DEF$ is congruent to triangle $GHI$, we need to prove that triangle $ABC$ is congruent to triangle $GHI$.

1. Problem Description

The problem describes the transitive property of triangle congruence. Given that triangle $ABC$ is congruent to triangle $DEF$ and triangle $DEF$ is congruent to triangle $GHI$, we need to prove that triangle $ABC$ is congruent to triangle $GHI$.

2. Solution Steps

The transitive property states that if $a = b$ and $b = c$, then $a = c$. This property can be extended to congruence.

Given:

$\triangle ABC \cong \triangle DEF$

$\triangle DEF \cong \triangle GHI$

Therefore, by the transitive property of congruence:

$\triangle ABC \cong \triangle GHI$

3. Final Answer

$\triangle ABC \cong \triangle GHI$