Answer:
It is 2√5
Step-by-step explanation:
[tex]{ \bf{ {(x - a) + {(y - b)}^{2} = {r}^{2} } }} \\ { \tt{ {(4 - 0)}^{2} + {(y - 0)}^{2} = {6}^{2} }} \\ { \tt{16 + {y}^{2} = 36}} \\ { \tt{ {y}^{2} = 20 }} \\ { \tt{ {y} = \sqrt{5 \times 4} }} \\ { \tt{y = 2 \sqrt{5} }}[/tex]
