(h, k) = center of circle
r = radius
Equation from a Graph
Examples
(x-4)2 + (y-3)2 = 36
center ( , ), radius =____
(x+4)2 + (y-3)2 = 16
center ( , ), radius =____
x2 + y2 = 4
center ( , ), radius = ____
Equations from Center and Radius
What is the equation of a circle with its center at
(3, 5) and a radius of 7?
What is the equation of a circle with its center at
the origin and a radius of 10?
Equations from Endpoints of the Diameter
Write the equation of a circle whose diameter’s endpoints are (1, 4)
and (-3, 2).
Midpoint Formula
What is the equation of a circle with its center at
(-1, 4) and a radius of 1?
Distance Formula