Hello, ilikewhoa!

What is the original wording of the problem?

There is an isosceles triangle with a base of 12 units.

Find the locus of points that are 6 units from the midpoint on the line.

. . What line?

If it refers to the midpoint of the base, why mention the triangle at all?

We have a line segment 12 units long.

The locus of points 6 units from its midpoint is a circle:

. . center at the midpoint, radius 6 units.