Equation of a Circle: Centre at (a;b) (Grade 12 NSC Matric Mathematics): Flashcards

Set of all points equidistant from a fixed centre point

$(x - a)^2 + (y - b)^2 = r^2$

$x^2 + y^2 = r^2$

The centre of the circle

$r^2 = (x-a)^2 + (y-b)^2$

Convert general form to standard form to find centre and radius

Replace x with (x - h)

Replace y with (y - k)

Midpoint of S and T

90°