A mathematics question that I need help with (1 Viewer)

[Skeptyks]

Hi, I just needed a tiny bit of help with this Mathematics/Extension 1: 3D Geometry question.

So pretty much, I used sine to find the 2 sides of the triangle located at the middle-ish area. Sin73 = 3000/x. Sin78 = 3000/y.
Afterwards, I found the top length to be 950/3 metres.
Then I used the cosine rule/formula for an angle, cosA = (b*2 + c*2 - a*2)/2bc.

Now the CORRECT answer is 11 Degrees 10 Minutes.
I was wrong by a mile.

Please correct my working out, sorry if it is vague and I appreciate anyone helping out :]

 

[AAEldar]

 

[Skeptyks]

Now I see it, I was looking at it with the wrong perspective. Thanks a lot!