# Lesson Plan: Equation of a Circle Mathematics • 11th Grade

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to find the equation of a circle using its center and a given point or the radius and vice versa.

#### Objectives

Students will be able to

• derive and recall the standard form of the equation of a circle, , and the general form, ,
• write the equation of a circle in standard form and general form given its center and its radius, or a point on its circumference,
• find the center of a circle and its radius given its equation in standard form,
• find the center of a circle and its radius given its equation in expanded form (by completing the square),
• find the equation of a circle given a wider geometric context such as the equation of a line that contains its center and points on its circumference.

#### Prerequisites

Students should already be familiar with

• the Pythagorean theorem,
• how to complete the square.

#### Exclusions

Students will not cover

• the vector form or parametric form of a circle.