Answer: True
Step-by-step explanation:
An equilateral triangle is a triangle with all its three sides are equal.
When we divide it into two equal halves, there will obtain a line of symmetry.
This line of symmetry is the perpendicular bisector of the side of triangle and thus it is the altitude of the triangle.
Therefore, its true that an equilateral triangle has symmetry with respect to a line containing an altitude of the triangle.
