Mathematics - Additional - 0606 CIE

The Equation Of A Circle

Overview

A circle is the set of points a fixed distance from a centre, and that simple idea becomes a neat equation. Once you can read a circle's centre and radius from its equation, a whole family of coordinate-geometry problems opens up.

In this lesson you will know and use the equation of a circle with centre \((a, b)\) and radius \(r\), and identify the centre and radius from a circle equation in any form.

Objectives

  1. Know and use the equation of a circle with centre (a, b) and radius r, in the forms (x - a)^2 + (y - b)^2 = r^2 and x^2 + y^2 + 2gx + 2fy + c = 0.
  2. Identify the centre and radius of a circle from its equation in any form.

Lesson Note

The circle equation links algebra and geometry, and is the starting point for tangents, intersections and many problems in this section.

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Lesson Evaluation

Congratulations on completing the lesson on The Equation Of A Circle. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

  1. The centre of (x - 3)^2 + (y - 2)^2 = 4 is: A. (-3, -2) B. (3, 2) C. (3, -2) D. (2, 3) Answer: B
  2. The radius of (x - 3)^2 + (y - 2)^2 = 4 is: A. 2 B. 4 C. 8 D. 16 Answer: A
  3. The standard circle equation is based on which theorem? A. factor theorem B. Pythagoras' theorem C. remainder theorem D. binomial theorem Answer: B
  4. In x^2 + y^2 + 2gx + 2fy + c = 0, the centre is: A. (g, f) B. (-g, -f) C. (2g, 2f) D. (g, -f) Answer: B
  5. The radius of (x - 1)^2 + (y + 2)^2 = 25 is: A. 5 B. 25 C. 10 D. 12.5 Answer: A

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
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Available on Android, Windows, macOS, and Linux

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
AI-powered learning assistant
Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Practice Mock Questions

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