SOLUTION: Find the center and the radius of x^2+y^2-8x+6y+9=0

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Find the center and the radius of x^2+y^2-8x+6y+9=0      Log On


   

Question 372618: Find the center and the radius of x^2+y^2-8x+6y+9=0
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi,

The standard equation of a circle with center C(h,k) and radius r is :

%28x+-+h%29%5E2+%2B+%28y+-+k%29%5E2+=+r%5E2

Find the center and the radius  

x^2+y^2-8x+6y+9=0

completing the squares

x^2-8x +   y^2+6y         +9=0

(x-4)^2 + (y+3)^2 -16 -9 + 9 = 0

(x-4)^2 + (y+3)^2 = 16 = 4^2

radius = 4, center (4,-3)