How to Calculate the Horizontal Distance in This Curvilinear Motion Problem?

[Jason03]

heres the diagram for the problem..

i14.photobucket.com/albums/a322/guitaristx/asdf.jpg


Im just trying to find the horizontal distance the water hits the building at...the answer should be in terms of horizontal distance from point B.

Heres my work...any suggestions would be great...

i14.photobucket.com/albums/a322/guitaristx/adsfffff.jpg

 

[Jason03]

any ideas?