I need help

Triangle WXY has side lengths XY = 14 and WX = 8. The tangent to the circumcircle of triangle WXY at X is drawn, and the line through W that is parallel to this tangent intersects XY at Z. Find YZ. 

Asymptote code:

[asy]
unitsize(2 cm);

pair A, B, C, D;

A = dir(110);
B = dir(210);
C = dir(330);
D = extension(B, C, A, A + rotate(90)*(B));

draw(Circle((0,0),1));
draw(A--B--C--cycle);
draw((B + rotate(90)*(B))--(B - rotate(90)*(B)));
draw(A--(A + 2.2*(rotate(90)*(B))));

label("$W$", A, N);
label("$X$", B, SW);
label("$Y$", C, SE);
label("$Z$", D, SW);
[/asy]

Thanks. I would not like the answer, I would like a solution, because I would really want to understand.