Equation of a circle.
The general form for the equation of a circle is \(ax^2 + by^2 + cx + dy + e = 0\), and the circle-radius form of the circle equation is \((x–h)^2 + (y–k)^2 = r^2\) , with the center being at the point \((h, k)\) and the radius being “\(r\)”.
Think about the following question. The endpoints of the diameter of a circle are \((-4, 0)\) and \((4, 0)\). What are the coordinates of the center of this circle?
