5.
http://s1239.photobucket.com/albums/ff509/axellink13/?action=view&current=93288-3112005-21159-PM-182232173.gif
when I did it I got 2.5 as my answer.

Axellink,

Welcome to this beautiful and great site, first!

Here, in the given triangle, I think you want to find out the value of x, but dear, here, if we divide the whole triangle into two parts (as it has been), we find that in the left handed trinagle, which is a right angled triangle, the

Hypotenues = 10,
Base = 5
So, the prependicular = 5 underroot 3

But, x is in the second triangle, in which we know nothing about the value of hypotenues, so it is difficult... rather impossible to find/figure out the value of x...

But, if you want anything else, just write here.