The triangular diagram, which was originally built on a foundation of bread, crackers and cereal, was replaced by a quartered circle called MyPlate, which emphasizes vegetables and grains equally.

The triangle diagram displayed in the center is interactive, and you can rotate or stop it by clicking the upper left corner, and you can adjust the position by clicking and dragging each vertex.

The chapters dealing with the first two elements do not call for special comment, although it may be noted that triangular diagrams are used extensively to illustrate the properties of ternary ...

Let's take a look. Here's a diagram of a large triangle made up of lots of smaller triangles. Can you work out how many triangles there are in this figure altogether? Explain your solution in detail.