+2666 We can rewrite this as: \(x^2-10x+y^2+16y=0\)
We can now complete the square, and add the remainder to the right-hand side: \((x-5)^2+(y+8)^2=64+25\)
In a circle's equation, the right-hand side is equal to \(r^2\), where r is the radius.
This means \(89 = r^2\)
Can you take it from here?
