In this chapter, we're going to be constructing regular polygons. The term regular means the polygons have all equal sides. If I want to make a triangle, that's easy, I can just draw three lines. But if I want to draw a regular triangle, that's more challenging, because all three sides have to be equal. So I'm going to reset. To do that.

I'm going to draw a circle. And then I'm going to draw a line from the center of the circle over and that creates points A, B and C. And then I'll draw another circle from B to A. So now I have the vesica viscous form. And I can construct a regular equal lateral triangle in here. That triangle is determined by its edge length A, B. So you can use this method if you want to create an equilateral triangle if you know the edge length.

However, what if you don't know that and you want to create a regular triangle inside of a circle. I'll show you another method for that. I'll just back up a little bit. And then I will draw an additional circle over here, which I will label D. And then I can draw a triangle in here and I can draw a matching triangle over here. So that's a method just using three circles. You can use to inscribe a regular triangle, also known as an E lateral triangle inside a circle