That is, the circle (x+4) 2+(y-5) 2 = r 2 is tangent to the X axis.

Therefore, the center of the circle is (-4,5) and the radius of the circle is r=5.

So the equation of a circle is, (x+4) 2+(y-5) 2 = 5 2.

If the circle intersects the y axis, let x=0.

Therefore, 4 2+(y-5) 2 = 5 2.

(y-5)^2=9

Y=8 or y=2

8-2=6, that is, the chord length obtained by cutting the Y axis of this circle is 6.