Question

What is the radius of a circle with center (2,1) and containing point (0,1)

Answer 1

The radius is 2 or The simplified radius is 4 ( if needed).

Explanation:

- The equation of a circle is:

`(x-h)^2+(y-k)^2=r^2` where the center is
`(h,k)`, the point as
`(x,y)` and the radius
`r^2`.

-Put both the center and the point onto that equation:

`(0-2)^2+(1-1)^2=r^2`

-Then, solve them up:

`(0-2)^2+(1-1)^2 =r^2`

`(-2)^2+0=r^2`

`4 + 0=r^2`

`4 = r^2`

`√(4) =√(r^2)`

`2=r`