Equations of circles?

Question

Find an equation of the circle that has center (-3,6) and passes through (4,-1)

Answer 1

The equation of a circle is

 

(x - h)² + (y - k)² = r²

 

where:

(h, k) is the center point

r is the radius

 

Therefore,

 

(3, -6) is the centerpoint of the circle.  The distance between the centerpoint and the point the circle passes through is the radius.

 

To find the radius, use the distance formula.