is the equation of a circle centered at with radius
Take your standard form equation and complete the square on each of the variables.
First move the constant to the RHS and group like variables:
Take the coefficient on the first degree term, divide by two, square the result, and add the squared result to both sides. Do the same thing with the variable.
Factor the two perfect square trinomials and collect terms in the RHS:
From which you can determine the center by inspection and the radius by taking the positive square root of the RHS.
John
My calculator said it, I believe it, that settles it
