How can I find the centre and radius from any form of the equation of a circle?
- A circle equation in a different form can always be rearranged into (x- a)2 + (y - b)2 = r2 form in order to find the centre and radius
- This will often involve completing the square
Exam Tip
Make sure you are able to rearrange circle equations given in the general form
x2 + y2 + 2fx + 2gy + c = 0
Worked Example
