1. Let's start by stating the problem: We need to understand the basics of circles in math. 2. The general equation of a circle with center at $(h,k)$ and radius $r$ is given by: $$ (x - h)^2 + (y - k)^2 = r^2 $$ 3. Important rules: - The center of the circle is the point $(h,k)$. - The radius $r$ is the distance from the center to any point on the circle. 4. Example: If a circle has center at $(3, -2)$ and radius $5$, its equation is: $$ (x - 3)^2 + (y + 2)^2 = 25 $$ 5. To find if a point $(x_1,y_1)$ lies on the circle, substitute into the equation and check if the equality holds. 6. If you want to find the radius given the center and a point on the circle, use the distance formula: $$ r = \sqrt{(x_1 - h)^2 + (y_1 - k)^2} $$ 7. This covers the fundamental concepts of circles needed for your SBA.