To launch the demonstration, click on the large button in the top-right corner of this page labelled "Demo". After a little while, two windows should appear; one will be labelled "Triangle" and the other will be untitled.

In the "Triangle" window, you will see a triangle (in white) and its corresponding midpoint triangle (in red). You can drag the vertices of the original triangle around; the areas of the two triangles and their ratio will automatically be calculated and displayed in the other window.

You may notice that the areas are sometimes negative. This is because we are calculating the oriented area. If you are not familiar with this concept, you may want to read the introduction to oriented area.