Question 475912
This is what I have from your description:


{{{drawing(300,300,0,10,0,10,


line(1,1,4,5),
locate(1,1,Z),
locate(4,5,Y),
line(6,3,6,6),
locate(6,3,C),
locate(6,6,X),
line(6,3,8,3+sqrt(12)),
locate(8,3+sqrt(12), D),
locate(2.5,3,5),
locate(6.1,4.8,3),
locate(7,4.6,4),
line(6,6,4,5)
)
}}}


This is why you have to post the full question (including diagram or thorough description of it so that anyone can understand), because I don't have your textbook in front of me. The "diagram" I posted above follows all the given constraints, but finding XY is impossible.