What is the general form of the equation that represents a circle?

The general form of the equation that represents a circle is given by (x - a)² + (y - b)² = r², where (a, b) represents the coordinates of the center of the circle, and r represents the radius. This equation is derived from the distance formula, as a circle is the set of all points that are a fixed distance (the radius) from a central point.

In the equation, (x - a)² indicates the horizontal distance from the center to any point on the circle, squared to ensure all distances are positive. Similarly, (y - b)² represents the vertical distance, also squared. When you add these two squared distances together, it equals the square of the radius (r²), establishing the relationship that defines a circle.

This form clearly shows how the position of the center and the size of the circle are encapsulated in a simple mathematical expression. Other forms provided in the choices do not represent the properties of a circle accurately, whether through incorrect arrangement or the absence of essential components like the center and radius relationship.