Which set of side lengths represents a triangle with 3 lines of reflectional symmetry?

A triangle has 3 lines of reflectional symmetry only when it is equilateral, meaning all three side lengths are equal. In choice C, the sides are 5, 5, and 5, so each line from a vertex to the midpoint of the opposite side is a line of symmetry. The other choices are not equilateral triangles.

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