You seem to be asking "If I have a circle with radius 10 centered at {-90, 27} what is its height at x=33.677. Put like that it should be pretty obvious that there will be no solution except for -100<x<80.
Also having b2 in the answer suggests your code does not do say what you say it says. b2 is coming from somewhere. I suggest you post the code in its entirety.
