Khan Academy
Khan Academy: Write Standard Equation of a Circle
Given the graph of a circle or its features, find its standard equation. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Center and Radii of Ellipses From Equation
Find the center and major and minor radius of an ellipse given its equation. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
CK-12 Foundation
Ck 12: Analysis: General Forms of Conic Sections
[Free Registration/Login may be required to access all resource tools.] This lesson covers changing a general second-degree equation into the standard form of a parabola, ellipse, circle or hyperbola. Students examine guided notes,...
CK-12 Foundation
Ck 12: Geometry: Circles in the Coordinate Plane
[Free Registration/Login may be required to access all resource tools.] In this lesson students find the standard equation of a circle. Students examine guided notes, review guided practice, watch instructional videos and attempt...
CK-12 Foundation
Ck 12: Geometry: Circles in the Coordinate Plane
[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to graph circles and find the standard equations of circles. Students examine guided notes, review guided practice, watch...
Khan Academy
Khan Academy: Center & Radii of Ellipses From Equation
In this four-question quiz, find the center and major and minor radius of an ellipse given its equation.
Khan Academy
Khan Academy: Write Standard Equation of a Circle
Given the graph of a circle or its features, practice finding its standard equation.
Khan Academy
Khan Academy: Features of a Circle From Its Expanded Equation
Find the center and radius of a circle given the equation in expanded form.
Khan Academy
Khan Academy: Features of a Circle From Its Standard Equation
Find the center and radius of a circle given the equation in standard form.
CK-12 Foundation
Ck 12: Interactive Geometry: 10.2 Equations of Circles
Derive the equation of a circle with the help of the Pythagorean Theorem.
National Council of Teachers of Mathematics
The Math Forum: Analytic Geometry Formulas, Hyperbolas
At this site from the Math Forum, a brief overview on calculating various measures of segments, like the transverse and conjugate axes and the distance between foci, is given. Additionally, equations of hyperbolas in general, standard,...
National Council of Teachers of Mathematics
The Math Forum: Analytic Geometry Formulas, Ellipses
A brief overview from the Math Forum on calculating various measures of segments, like major and minor axes and distance from focus to center, is given. Additionally, equations of ellipse in general and standard forms are listed.
National Council of Teachers of Mathematics
The Math Forum: Circles
Various forms of equations of circles are presented at the Math Forum: center-radius form, general form, diameter form, three-point form, and parametric form.
Wolfram Research
Wolfram Math World: Radius
This math site from MathWorld.com defines radius in terms of both a circle and a sphere. The site includes a diagram and links to related topics.
Wolfram Research
Wolfram Math World: Circle
This site from Mathworld provides a wealth of information about circles is presented. The information ranges from the basics--radius, circumference, etc.--to advanced concepts--equations in polar and pedal coordinates, etc.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Deriving the Hyperbola Formula
Dr. Math tackles a question about deriving the formula for a hyperbola posed by a student.
Math Words
Math words.com: Conic Sections
Examples of conic sections are given and the equation for their standard form is also given.
Sophia Learning
Sophia: Equations for the Circle: Lesson 3
This lesson presents the standard form and the general form for the equation of a circle, and relates the two. It is 3 of 5 in the series titled "Equations for the Circle."
ClassFlow
Class Flow: Completing the Square Circles
[Free Registration/Login Required] This flipchart is a simple and basic flip chart showing how to find the center and radius of a circle that is in standard form as well as completing the square for equations of circles that are not in...
BBC
Bbc: The Circle
The equation of a circle is the focus of this site. Topics include tangents, intersecting circles, and intersection of lines and circles. Examples and a practice test are available.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Equations of Conics
Posed with a student question about equations of conics, Dr. Math provides some insight on the standard form of parabolas, ellipses, and hyperbolas. One example is shown.
Free Math Help
Free Math Help: Completing the Square in Circle Equations
This discussion examines how to complete the square in circle equations. Students learn about the math concept through definitions and examples with detailed solutions.
Wolfram Research
Wolfram Alpha: Conic Sections
The resource consists of a geometry animation that shows conic sections.