9514 1404 393
Answer:
about 1.4288993 radians
Step-by-step explanation:
The angle to terminal arm A is ...
∠A = arctan((-4/5)/(-3/5)) ≈ 4.0688879 radians
The angle to terminal arm B is ...
∠B = arctan((-1/√2)/(1/√2)) ≈ 5.4977871 radians
Then the angle between the arms is ...
5.4977871 -4.0688879 ≈ 1.4288993 . . . radians
