I ended up taking a lightly different approach....
From here, I can input one point and then h and k, and then solve that for r. Very simple, very quick. Thank you, though!
Uhm, someone, help, please?
Sorry; when you said you'd figured this out, I don't think anybody knew you were still wanting help. Oops!
a) Plug in the three points in the equation. Easy enough. -h^2 + -k^2, (1-h)^2 + -k^2, -h^2 + (2-k)^2
Actually, these aren't equations; they're expressions.
Instead, try following the step-by-step instructions provided earlier.
Note: The expression (0 - h)2
equivalent to -h2
To learn how negatives and exponents work, try here