Question

How do you find the center and radius of the circle with this equation `(x-2)^2 + (y+4)^2 = 9`?

Answer 1

The centre is `(2,-4)` and the radius is `3`.

Explanation:

Any cricel centred at `(a,b)` and with radius `r` has equation
`(x-a)^2+(y-b)^2=r^2`.

So in this particular case, `a=2, b=-4, r^2=9`

Therefore the centre is `(2,-4)` and the radius is `3`.