What is the form of the equation for a circle?

Question

Like y=mx+b gives us a line, y=m*abs(x)+b gives us a ray, y=ax^2+bx+c gives us a parabola, etc. What would give us a circle and/or an oval?

Answer 1

For a circle the equation is:
(x-a)^2 + (y-b)^2 = r^2

r is the radius, a, b, are the coordinates of the centre

An elipse is more complicated see here:

http://en.wikipedia.org/wiki/Elipse

Answer 2

The equation of a circle is (x-h)^2 + (y-k)^2 = r^2, where (h,k) is the center of the circle and r is the radius. An oval is an ellipse, but I don't remember the formula for that exactly...

Answer 3

x^2 + y^2 = r^2 is a circle.
r is radius.
x^2/a^2 +- y^2/b^2 = 1 is the general formula for all conic sections.
2a is the major axis
2b is the minor axis
of an ellipse (and the sign is plus).
2b is the conjugate (imaginary) axis of a hyperbola (and the sign is minus)..
I forget how they get a parabola out of it (if they do).


edit
I am curious about what the mistake was that got me the thumbs down. Email me if you have an explanation.

Answer 4

(x-a)^2+(x-b)^2=r^2 is the equation of a circle
[(x-a)^2]/k + [(x-b)^2]/m = r^2

Answer 5

(x-h)^2+(y-k)^2=r^2 R is radius, center point is (H,K).

Answer 6

yes