Circle Equation Calculator

Convert from center-radius form to general form and visualize the circle.

Enter Circle Details

Specify the center coordinates (x, y) and the radius of the circle to calculate its general equation.

Understanding the Circle Equation

The equation of a circle is a fundamental concept in geometry. A circle is defined as the set of all points in a plane that are equidistant from a given point called the center. This fixed distance is the radius of the circle.

Center-Radius Form vs. General Form

The center-radius form of a circle's equation is given by: $$ (x-h)^2 + (y-k)^2 = r^2 $$ where (h, k) are the coordinates of the center and r is the radius.

The general form of a circle's equation is: $$ x^2 + y^2 + Cx + Dy + E = 0 $$ This calculator converts from center-radius form to general form, making it easy to see the expanded polynomial representation of the circle's equation. You can use this tool to quickly get the general form equation for any circle given its center and radius.

How to Use This Calculator