Since XZ is a common tangent, it is perpendicular to both XW and ZY.
Draw a line parallel to XZ passing through W and intersecting ZY at V.
Then VZ=11, VY=19-11=8.
Calculate WY using Pythagoras Theorem,
[tex]WY=\sqrt{WV^2+VY^2}=\sqrt{42^2+8^2}=\sqrt{1828}=42.755[/tex]
