A-Math: General Equation of Circle - Linked to Completing Square

In the previous post, I have discussed the standard equation of circle which is derived from distance formula.

The other equation of circle is known as General.



To answer this question easily, you need your completing square technique (Read about the steps here) which many students dislike!

You notice in the step by step solution, the general equation is converted into a standard equation through the following steps:

  1. Arrange all x terms and y terms together
  2. Start completing square
  3. Simplify all constants
  4. Set equation into standard equation of circle

General Equation to Standard Equation of Circle


Radius = 5 and Centre of circe = (4, 1)

I hope you have a better understanding on equation of circle.

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Hi, I'm Ai Ling Ong. I enjoy coaching students who have challenges with understanding and scoring in 'O' Level A-Maths and E-Maths. I develop Math strategies, sometimes ridiculous ideas to help students in understanding abstract concepts the fast and memorable way. I write this blog to share with you the stuff I teach in my class, the common mistakes my students made, the 'way' to think, analyze... If you have found this blog post useful, please share it with your friends. I will really appreciate it! :)

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