Answer :
Not enough information in order to solve. Need to know where a and b are
Answer:
56.9°
Step-by-step explanation:
Assuming you mean a and b as the legs of a right triangle and θ as the bigger angle in a right triangle, we can work out easily that
cos θ = 6/11
so θ ≈ 56.9°(to 1 d.p.)