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Phillcon1 · Apr 12, 2012, 06:53 AM

p(-3,-3), q(9,13)

ebaines · Apr 12, 2012, 08:13 AM

Not sure what the 'p' and 'q' are supposed to mean - is 'p' the center and 'q' a point on the circle?

The general form for a circle is

$<br /> R^2 = (x-x_0)^2 + (y-y_0)^2<br />$

where $(x_0, y_0)$ is the center of the circle and R is the radius. You can get the radius using Pythagorus: if $(a,b)$ is a point of the circle and $(x_0,y_0)$ is the center, then

$<br /> R^2 = (a-x_0)^2 + (b-y_0)^2<br />$

Do you see why that is?