Got an update. My friend and I went in and asked the teacher for some help at lunch. She said that the square of the length of RT equals (2x^3)/(2x-8.5). She said that showing why that is is still up to us. This helped me get through the other parts of the problem, but I still can't figure out where that expression comes from. I feel like I'm missing something obvious or easy or something. I'm trying to work backwards from the expression, but I can't find any of the measures I figured-out at first in there no matter how I manipulate it. Maybe I'm still going about this all wrong, but I still don't have any better ideas.