Question

which set of side lengths represents a triangle with 3 lines of reflectional symmetry? 5,10,5; 3,4,5; 5,5,5; 3,6,9

Explanation:

Step1: Identify triangle types

Equilateral triangles have 3 reflectional symmetry lines.

Step2: Check side lengths

5,5,5 are equal (equilateral). 3,4,5 (scalene, 0 lines); 5,10,5 (invalid, 5+5=10); 3,6,9 (invalid, 3+6=9).

Answer:

5,5,5