bearisgray

You will (theoretically) need to cut 20 sections/segments of the 18 degree ruler for the 360 degree circle on the "other" side.

Are you plannning to make this as a round circle? Then there would be no hassle of attempting to line up a six segment side to a 20 segment side.

Anyway - depending on how you choose to line up the designs of the six segments -

Approximate dimensions:

For a 44 inch (finished) diameter skirt:

Maximum length of fabric would be 22 inches plus seam allowances - I would go with 24 inches of fabric - 1/2 diameter plus seam allowances

Minimum length would be "height"* - which would be the(square root of( 22 squared - minus 11squared )) + seam allowances

square root of (484 - 121) + seam allowances

square root of 363 + seam allowances
19.06 + 1/2 to 3/4 inch

Approximately 20 inches for "height"

I checked four of my rulers to see how the 60 degree line was placed - one had the angle lines starting at the center of the ruler, two of them had the angle lines start at the corner of the ruler, and one had the angle lines start "somewhere" on the sides of the ruler.

The "approximate" height of an equilateral triangle is about 0.9 times the length of a side. Example: (0.9 x 22) = 19.8

The "less approximated" height of an equilateral triangle is about 0.87 times the length of a side. Example: (0.87 x 22) = 19.14

In my opinion, for most quilting projects, rounding up at the second decimal point when doing calculations is "close enough" .

Scale is approximate on drawing. I should have made it a bit taller than I did.