SOLUTION: Hi Guys, really struggling with this question. Given the Cartesian equation of a circle in the form x^2+y^2+8x-8y+16=0 Find by completing the squares, the centre coordinates

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: Hi Guys, really struggling with this question. Given the Cartesian equation of a circle in the form x^2+y^2+8x-8y+16=0 Find by completing the squares, the centre coordinates      Log On


   

Question 357301: Hi Guys, really struggling with this question.
Given the Cartesian equation of a circle in the form
x^2+y^2+8x-8y+16=0
Find by completing the squares, the centre coordinates of the circle and its radius, Hence sketch the graph of the circle taking care to label the x-axis and y-axis and the origin.
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 

completing the square

x^2+y^2+8x-8y+16=0

x^2+ 8x +16 + y^2-8y +16 -16=0

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

Center of the circle is Pt(-4,4) and the circle has a radius of 4