Art of Modern Earth - How Crop Circle Created - Step Two : Designing the Drawing - The Polygon

The next element of crop circle we need to know is the polygon. The most appearance of polygon used in early artists CC designs are equilateral triangle, square, the pentagon, five-pointed star (pentagram), the hexagon, six-pointed star (hexagram) and others.

Here is how to construct an equilateral triangle 

Constructing Equilatereal Triangle

In order to construct  an equilateral triangle, you need to draw 4 same diameter auxiliary  circles. And each circle has 2 constraint, i.e : center circle position (point1, 2, 3a and 3b) and the diameter. the step in constructing the triangle (this is the algorithm to draw perfect equilateral triangle):