The required angles are
sin 49 = a/c sin 51 = b/c
cos 49 = b/c cos 51 = a/c
tan 49 = a/b tan 51 = b/a
How to find the angles
The angles are solved using trigonometry
Sin = opposite / hypotenuse - SOH
Cos = adjacent / hypotenuse - CAH
Tan = opposite / adjacent - TOA
sin 49 = a/c
sin 51 = b/c
cos 49 = b/c
cos 51 = a/c
tan 49 = a/b
tan 51 = b/a