# Equation of Circle

Videos and lessons to help High School students learn how to derive the equation of a circle of given center and radius using the Pythagorean Theorem; complete the square to find the center and radius of a circle given by an equation.

Common Core: HSG-GPE.A.1

Equation For a Circle
This lesson shows two examples regarding how to find the equation of a circle centered at the origin.

Derive the equation of a circle using the Pythagorean Theorem - G-GPE.1
In this lesson, we will learn how to derive the equation of a circle using the Pythagorean Theorem.

Change equations into the standard form of a circle
In this lesson, you will learn how to change an equation into the standard form of a circle by completing the square.

Completing the square to write equation in standard form of a circle.

Find the center and radius of a circle - G-GPE.1
In this lesson, you will learn how to find the radius and center of a circle by looking at the equation.

Radius and center for a circle equation in standard form.

Standard Form of the Equation of a Circle
This Demonstration shows the standard form of the equation of a circle as you change the coordinates of the center and the radius.

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You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.