Triangle. Line bisects one side and parallel to second
Practical proof of a Triangle Theorem. A line bisecting one side of a triangle, drawn parallel to the second side of the triangle, bisects the third side. Normally, the learner has to prove this analytically, but sometimes the very theorem (principle) not being clear to the learner. The Teacher is able to demonstrate that the third side is always bisected for all sizes and shapes of triangles.