A few tips for the future- do NOT use all caps- it makes it look like you are "yelling". As much as possible, type what your problem is- many people will not open attached files- there is always a danger of a computer virus. Finally, if this problem has stumped you "a little" then you must have tried something. Show what you have tried so we will know better what hints will help.
Now, as for this problem- you have two right triangles where the hypotenuse of one is a leg of the other. The result you want involves cosines of two of the angles. I would start by assigning labels to each side, write out the definition of "cosine" in terms of the sides and stare at them until inspiration hits.