Points Inside, Outside or On a Circle (Leaving Cert Mathematics): Flashcards

$(x - h)^2 + (y - k)^2 = r^2$

$d = \sqrt{(x - h)^2 + (y - k)^2}$

$(x - h)^2 + (y - k)^2 = r^2$ or $d = r$

$(x - h)^2 + (y - k)^2 < r^2$ or $d < r$

$(x - h)^2 + (y - k)^2 > r^2$ or $d > r$

Substitute coordinates into equation and compare with $r^2$

Compare $(x - h)^2 + (y - k)^2$ with $r^2$

On the circle

Inside the circle

Outside the circle