Equation of Circle

  • From: Zobeyda
  • Date: 15 October 1999
  • Subject: Equations of Circles

I need to put together the equation of the circle with centre (-8, 2) and radius 6

Please include formulas and steps, so I can learn and practise.


Maths Help suggests:

The formula for a circle of radius r  and centre (a, b)  is:

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

Your values are:   a = -8,   b = 2   and   r = 6

So (taking care with the signs) the equation of your circle is:

(x + 8)2 + (y - 2)2 = 62

I prefer not to expand this equation (by squaring each term).
The resulting equation will not look any simpler; and will not be easily recognised as the equation of a circle.

Return to contents list