Answer:
15 units
Step-by-step explanation:
The picture of the question in the attached figure
we know that
Triangle XYZ is a right triangle, because segment ZY is tangent to circle X at point Y
so
Applying the Pythagorean Theorem
[tex]XZ^2=XY^2+ZY^2[/tex]
we have
[tex]XZ=8+9=17\ units\\XY=8\ units[/tex]
substitute the given values
[tex]17^2=8^2+ZY^2[/tex]
[tex]ZY^2=289-64\\ZY^2=225\\ZY=15\ units[/tex]
