AQA A Level Maths: Pure复习笔记3.2.1 Equation of a Circle

Equation of a Circle

 

What do I need to know about the equation of a circle?

  • A circle with centre (a, b) and radius r has the equation

3.2.1-Eqn-of-Circle-graph-illustr

  •  You need to be able to find the centre and radius of a circle from its equation

3.2.1-Eqn-of-Circle-Illustr-1

 

  •  You need to be able to find the equation of a circle given its centre and radius

3.2.1-Eqn-of-Circle-Illustr-2

Exam Tip

  • Remember that the numbers in the brackets have the opposite signs to the coordinates of the centre. 3.2.1-Eqn-of-Circle-sign-flip
  • Don't forget to take the square root of the right-hand side of the equation when finding the radius.

Worked Example

3.2.1-Eqn-of-Circle-Example

转载自savemyexams

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