What sides have to be congruent in order to use the theorem?
Your friend is incorrect. Explanation: See solution.
Practice makes perfect
According to the SSS Congruence Theorem, if three sides of one triangle are congruent to three sides of a second triangle, then the two triangles are congruent. This does not require two triangles to be equilateral triangles where all sides are congruent. As long as corresponding sides are congruent, the theorem can be used.
