Question 1207918
A

iven:
•	Center: (1,0)

•	Point on the circle: (−3,2)
We find the radius r by  the distance between the center and the given point by the distance formula:
r=sqrt((x2−x1)^2+(y2−y1)^2)

Substitute the given coordinates 

r=sqrt((−3)−1)^2+(2−0)^2)
r = sqrt(20)
r= 2 sqrt(5)

Equation of circle 
(x-1)^2+ (y-0)^2 = (2sqrt(5))^2

(x-1)^2+y^2= 20  ---------------------------A


Given: center (−3,1)
Tangent to the y-axis
Since the circle is tangent to the y-axis, the radius r is the horizontal distance from the center to the y-axis. The x-coordinate of the center is −3 

so the radius  𝑟 =3

(x−(−3)) ^2  +(y−1) ^2 = 3^2=9

(x+3)^2 +(y-1)^2 = 9