Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Circle - Equation

The equation for a circle

Sponsored Links

Circle - equation

Unit Circle

The equation of a unit circle - where the center of the circle is located in the origo of the coordinate system and the radius = 1 - can be expressed as

x2 + y2 = 1                                (1)

Standard Form

The standard form for the equation of a circle can be expressed as

(x - a)2 + (y - b)2 = r2                            (2)


a = x coordinate position of the circle center

b = y coordinate position of the circle center

r = circle radius

General Form

The general form for the equation of a circle can be expressed as

x2 + y2 + A x + B y + C = 0                                  (3)


A, B, C = constants

Radius of circle

r = (a2 + b2 - C) 1/2                                       (4)

Coordinates in the Circle Centre

a = - A / 2                                   (5a)

b = - B / 2                                   (5b)

Sponsored Links

Related Topics

Related Documents

Tag Search

  • en: circle equation
  • es: círculo ecuación
  • de: Kreisgleichung
Sponsored Links

Search the Engineering ToolBox

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse!

Translate this page to
About the Engineering ToolBox!


This page can be cited as

  • Engineering ToolBox, (2014). Circle - Equation. [online] Available at: [Accessed Day Mo. Year].

Modify access date.

Customize Ads in the ToolBox

Make ads more useful in Google Ad Settings .

. .


3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Scientific Online Calculator

Scientific Calculator

11 2

Sponsored Links