https://www.schoollearners.com/theorem-8-10-class-9-the-line-drawn-through-the-mid-point-of-one-side-of-a-triangle-parallel-to-another-side-bisects-the-third-side/
Class 9 Chapter 8 Theorem 8.10 The line drawn through the mid-point of one side of a triangle, parallel to another side bisects the third side.