Grab a pen and draw a figure. Follow a few rules: keep your lines straight, don’t pick up your pen, don’t cross the lines, and finish at the spot where you started. You’ll have a polygon. Polygons are ...

A nonagon has nine sides and a decagon has ten sides. To understand polygons, a good understanding of other angle rules, including triangles and quadrilaterals can be helpful. The word for the name of ...