Details or link to this magic number?
Several years ago, I learned about this number, which can be multiplied by any regular polygon's perimeter squared to get the polygon's area. I learned this number as the Greek letter phi, which can be multiplied in the correct subscript to a figure's perimeter squared to get its area (for example, you would multiply phi with a subscript of 5 to the perimeter of a regular pentagon squared to get its area. I can't find a link anywhere talking about this concept or number or whatever it is, so could anyone please explain it to me or link me to an explanation? Thanks!
I'm not talking about the golden ratio here. but something else, which I'm not quite sure of.