It creates a regular star shaped PolyCurve from given.
From above image, a formula can be found as follow.
r2 = (r1*cos(360/n)) / cos(180/n)
I wanted to input the formula at a Formula node as it is.
But I couldn't. Because the Formula node in Dynamo reads angle values as Radians.
There are some options to deal with it.
1. Calculate cos values first. Math.Cos node reads values as degrees.
2. Convert degrees to radians first.
3. Use 'pi' for radians.(180 degree is 'pi')
You can find the package as usual. (Search 'RegularStar')