star figure

The star figure is a variation on the star polygon.
Star figure or star polygon is sometimes called a polygram.

Given a regularly placed points on a circumference. By connecting each b^th point, a star figure (a,b) is formed when a and b are not relatively prime.
The curve consists of two or more (simple) polygons.

Some examples:

• a=6, b=2: the hexagram, also named star of David or Jews' star (a=6, b=2), named to the Jewish king David, is the symbol of the Jews.
  The curve is a combination of two triangles.
  
  
  
  
  
  
  
  
• a=8, b=2: the star of Lakshmi.
  It represents Ashthalakshmi, the eight forms of the Hindu goddess of fortune and prosperity named Lakshmi.
  The curve is a combination of two squares.
  
  
  
  
  
  
  
• a=9, b=3: nonagram or star of Goliath
  The curve is composed of three equilateral triangles rotated at angles 0, 40 and 80 degrees.