ANSWER
The radius is 4
EXPLANATION
The given equation is:
[tex] {x}^{2} + {y}^{2} - 10y + 6x + 18 = 0[/tex]
We complete the square to get the expression in standard form:
[tex]{x}^{2} + 6x + {y}^{2} - 10y + 18 = 0[/tex]
[tex]{x}^{2} + 6x + 9 + {y}^{2} - 10y + 25 = - 18 + 9 + 25[/tex]
We factor using perfect squares to get:
[tex]{(x + 3)}^{2} + {(y - 5)}^{2} = 16[/tex]
This implies that,
[tex]{(x + 3)}^{2} + {(y - 5)}^{2} = {4}^{2} [/tex]
Comparing to
[tex]{(x - h)}^{2} + {(y - k)}^{2} = {r}^{2} [/tex]
The radius is r=4
