My problem is essentially that I do not understand Mathematica.
Currently, I'm trying to find a circle tangent to two circles and a line. I found the PDF linked to this post which gave me a big hand with the formulas involved, but actually solving them is a bit of a pain. I started crunching by hand, but when the lines started exceeding the page width, I turned to Wolfram|Alpha... which told me that my inputs were too long, so I downloaded the Mathematica trial, which I can't figure out.
I'll take some general pointers on this; I don't need a fully formed solution (I think). My attempts at using Solve and Reduce and Plot are giving me errors like "Tensors have incompatible shapes", "... is not a quantified system of equations and inequalities", and "... is not a valid variable". I don't even know what a tensor *is*, so I'm obviously missing something here.
If it helps to describe things, the current goal is to find a circle tangent to:
(x-(sqrt(2)-1))^2 + (y-(sqrt(2)-1)^2=(sqrt(2)-1)^2