# Center and radius of a circle

## Circle equation review

In this lesson you will learn how to find the center and radius of a circle.

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To begin, we need to remember how to find distances. Starting with the Pythagorean Theorem, which relates the sides of a right triangle, we can find the distance between two points. The Pythagorean Theorem states that the sum of the squares of the legs of a right triangle will equal the square of the hypotenuse of the triangle. So first we ask, what is a circle? A circle is a set of points equidistant from a center point. A common form to write the equation of a circle in is the center-radius form.

Completing the Square: Circle Equations. This form of the equation is helpful, since you can easily find the center and the radius. This lesson explains how to make that conversion. Completing the square to find a circle's center and radius always works in this manner. Always do the steps in this order, and each of your exercises should work out fine.

## Circle equation calculator

This calculator can find the center and radius of a circle given its equation in standard or general form. Also, it can find equation of a circle given its center and radius. The calculator will generate a step by step explanations and circle graph. Welcome to MathPortal. I designed this web site and wrote all the lessons, formulas and calculators. If you want to contact me, probably have some question write me using the contact form or email me on.

Draw a curve that is "radius" away from a central point. Circle: The set of all points on a plane that are a fixed distance from a center. There are an infinite number of those points, here are some examples:. So the circle is all the points x,y that are "r" away from the center a,b. Now lets work out where the points are using a right-angled triangle and Pythagoras :.

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## Features of a circle from its standard equation

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1. Coisurengui says:

Demonstrates how to complete the square to find the center and radius of a circle . Points out common mistakes.

2. Tactstudrushoa says:

3. Patricia W. says: