Question

How do you find the center and radius of the circle `(x+9)^2 + (y-5)^2 = 64`?

Answer 1

centre (-9 ,5) , radius = 8

Explanation:

The standard form of the equation of a circle is.

`color(red)(|bar(ul(color(white)(a/a)color(black)((x-a)^2+(y-b)^2=r^2)color(white)(a/a)|)))`
where (a ,b) are the coordinates of the centre and r, the radius.

From the given equation we should see that

a = -9 , b = 5 and r = 8

hence centre = (-9 ,5) and radius = 8