Question

How do you write the equation for a circle with Center of circle (-3,9) radius with endpoint (0,7)?

Answer 1

`(x+3)^2+(y-9)^2=13`

Explanation:

Standard equation for circle center `(a,b)`, radius `r` is `(x-a)^2+(y-b)^2=r^2`. The radius `r` is the distance from the origin to the end point of the radius, which by Pythagoras is `sqrt((-3-0)^2+(9-7)^2)=sqrt(13)`.