Angle between two lines (or triangle)

Question

Hello,

I would like calculate the angle between blue lines (see link).

http://imgur.com/IjQFp1B

Unfortunately i don't know lenghts of triangle on the left. It's actually suns' direction line. Both triangles have right angle. 

I appreciate, if i can get any help. 

Answer 1

Label in diagram is incorrect.
red angle is 5,87°, while small black angle is 6,801° yet small black angle is part of red angle.
If correct the process would be:
red angles - small black angle + large black angle = blue angle