Answer :
It depends how you name the sides of triangle.
Look at picture at the result.
[tex]cos\alpha=\frac{12}{13}\\ cos\beta=\frac{5}{13}[/tex]
PS. Sorry for my terrible drawing but I did it as fast as possible :)
Look at picture at the result.
[tex]cos\alpha=\frac{12}{13}\\ cos\beta=\frac{5}{13}[/tex]
PS. Sorry for my terrible drawing but I did it as fast as possible :)