Posted by **Shane** on Sunday, September 1, 2013 at 2:01am.

A circle x^2 + y^ + 2x - 2y -1 = 0 expressed in the following form (x-h)^2 + (y-k)^2 = r^2 where h, k are the coordinates of the centre. How is r the radius given?

- maths -
**Steve**, Sunday, September 1, 2013 at 1:12pm
eh? r is the radius. r = √r^2

Not sure what you mean by "how is r given?" Its square is part of the equation, as are h and k.

For this particular circle, we have

x^2+2x + y^2-2y = 1

x^2+2x+1 + y^2-2y+1 = 1+1+1

(x+1)^2 + (y-1)^2 = 3

so, r = √3

## Answer this Question

## Related Questions

- maths - A circle x^2 + y^ + 2x - 2y -1 = 0 expressed in the following form (x-h...
- maths - the circle is given by the equation x^2+y^2+8x-7/2y=0 find (i)...
- Maths - In an orthonormal system, you're given the following: Point P(1,2) Lina ...
- maths - 1) Circle centre (7,-2) passes through (-2,10). Calculate radius and ...
- Maths again - For the transformation w=z^2, show that as z moves once round the ...
- maths - given the following equation for a circle x^2-8x+y^2+4y+11=0 find its ...
- Maths - In polar coordinates, the parametric equations x=6+cos(f) and y=sin(f) ...
- Mathematics - In an orthonormal system, you're given the following: Point P(1,2...
- maths - Given that the equation of the circle is x^2+y^2+2x-8y+5=0 (i)find the ...
- maths - Given that the equation of the circle is x^2 + y^2 +2x -8y+5 =0 (i)Find ...

More Related Questions