star polygon

Given a regularly placed points on a circumference.
By connecting each b^th point, a star polygon (a,b) is formed.
A and b are relatively prime, as defined by Coxeter (1969).

Some examples:

• a=5, b=2: pentagram, also named pentacle, pentalpha or pentangle
• a=8, b=3: octagram
• a=10, b=3: decagram
• a=12, b=5: dodecagram

The curves were first studied by Thomas Bradwardine (1290-1349).

When a and b are not relatively prime, the curve is called a star figure.
Star figure or star polygon is sometimes called a polygram.