SOLUTION: what is the radius of the circle defined by the equation x^2+y^2-4x+18y+81=0 ?

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Question 629592: what is the radius of the circle defined by the equation x^2+y^2-4x+18y+81=0 ?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

x^2+y^2-4x+18y+81=0

(x-2)^2 + (y+9)^2 - 4 - 81 +81 = 0

 %28x-2%29%5E2+%2B+%28y%2B9%29%5E2+=+4+=+2%5E2  r = 2