Ahh...so:Do you see where to go now?
I find this to be one of the most frustrating things about math. It seems like so much of it is rooting around aimlessly in the hope of stumbling upon something. It seems like, for being an "exact" science, it should be more exact.When in doubt, do what you can with what you have, and see where that leads. With luck, you'll start seeing something helpful.