We are given an Isosceles triangle PQR
Recall that an isosceles triangle has two equal sides.
The medians are perpendicular to the opposite sides.
These medians divide the triangle into two congruent triangles.
The lateral sides are equal because of an isosceles triangle, the opposite sides are bisected and hence they are also equal, and lastly, one side is common to both so they are equal too.
Therefore, three equal sides mean that the triangles are congruent.
The correct statement is the last one.