I am trying to work through understanding a paper on an application of differential geometry and have become stuck on what is likely a trivial problem for someone here to assist with. The paper describes a set of five coefficients required to perform the calculation and I am having trouble figuring the 4th and 5th (c4 and c5). The image gives the specific formulas I am struggling through. I have also attached a link to the entire white paper in case you need further information. I am stuck where it says "Equations (6) and (9) lead to a quadratic equation for c4, ..." I'm not sure how to solve this system to produce a formula for c4 or c5 individually. Any assistance you can provide here is appreciated.