A circle passes A(-4,-1) and B(2,1). How do you find the center and radius of this circle if the center of the circle is on y-axis?

1 Answer
Mar 28, 2018

graph{x^2 +(y+3)^2=20 [-10, 10, -5, 5]}
Given that the center of the circle is on y-axis (x=0), let us consider the coordinates of its center (O) be (0,a)

So

OA2=OB2=R2,Where R is the radius of the circle.

42+(a+1)2=22+(a1)2=R2

(a+1)2(a1)2=2242

4a=12

a=3

Hence coordinates of the center (O) is (-3,0).

And radius R=22+(a1)2

R=22+(31)2=25