Answer
The vertex of an isosceles triangle is always intersected by the perpendicular bisector of the base.
Work Step by Step
We call the length of the base 2a, and we know that the vertex will have an x value of a. Thus, we find that when the bisector bisects the base, which is on the x-axis, it is a vertical line at x=a. Thus, it goes through the vertex of the trapezoid.
