derive formula from a sketch in Creo?

Hi there,

My autonomous vehicle programming colleague who want to program a u-turn just asked me if its possible to get the formula from my CAD sketch in Creo:

my input is sd17 and I would like to know what is the formula to get the resulting rsd18 (sd3 is locked)

I tried to get the formula by creating a list of input and output values and plotting the resultant graph with a trendline but that only gives an estimation and not the exact formula. Is there a way to get the actual formula that is used to get the value of rsd18?

We use Creo 5 (and Mathcad).