Question

What is the center and the radius of the circle: ( x + 6 ) 2 + ( y - 9 ) 2 = 121 ?

Answer 1

A circle with center at (h,k) and a radius of r has equation

$\left(x−h\right)^2+(y−k)^2=r^2.$

In this case our circle equation can be written as:

$(x-(-6))^2+(y-9)^2=11^2$

So, we have: h= − 6 , k = 9 and r = 11. The answer is d. Center = ( - 6,9) and radius = 11.