How to use this applet:
Enter the x and y co-ordinates of the points.
Click the calculate equation button to return the equation.
The Red lines are the lines between the points on the circle. The Blue lines are the perpendicular bisectors of the red lines, showing how they intersect at the centre of the circle.
Click reset to clear all values.
Notes on the maths used in the applet:
The circle equation is obtained in the following way:
1. Get the equation of two of the lines between the points.
2. Get the intersection of the perpendicular bisectors of these lines.
3. This point gives the centre of the circle.
4. The radius can be obtained by getting the distance between the centre and one of the three given points.
5. Substitute this information into the formula:
(x-h2 + (y-k)2 - r2 = 0, where the centre is(h,k),
and the radius is r.
