Let's apply the Law of Cosines here. We want the measure of the angle opposite the side with length 16.
Call that angle C.
Then 16^2 = 36^2 + 28^2 - 2(36)(28)cos C.
Solving for C: cos C = 16^2 - 36^2 - 28^2
------------------------- = 0.904, and C = 0.44 rad
-2(28)(36) or C = 25.21 degrees
So each of the 2 equal angles shown has the measure 25.21 degrees.
Unfortunately, I don't know the direction we should go from this point on.
