center at (h,k) and radius r is
(x-h)²+(y-k)²=r²
so given
center at (9,-8)
(x-9)²+(y-(-8))²=r²
(x-9)²+(y+8)²=r²
input the point (19,22) to find r²
x=19 and y=22
(19-9)²+(22+8)²=r²
10²+30²=r²
100+900=r²
1000=r²
10√10=r
well, the equation is
(x-9)²+(y+8)²=1000
