Circles Ch10.3 and additional material

Geometric Definition: The intersection of a cone and a plane.

Algebraic Definition: A set of points equidistant from a fixed point (center). y x (h,k) (x,y) r Radius (r) Center (h,k)

Circles have a standard conic form equation. Center: (h,k) Radius: r

Facts: Circle Equation  Both variables are squared.  Equation of a circle in center-radius form:  What makes the circle different from the line?  What makes the circle different from the parabola?

You can put an equation into standard conic form by completing the square. Remember that

Ex) Put the equation in standard form by completing the square.

Ex) Find the center and radius. Then graph. C: (3, -2) r: 5