At a point during the flight, a plane is 42 kilometres south and 57 kilometres west of the airport it left from.


Find the size of the angle marked b to one decimal place.
Please directly answer the question and provide the final value, e.g., 1, 2.5, 300.
Question: At a point during the flight, a plane is 42 kilometres south and 57 kilometres west of the airport it left from.


Find the size of the angle marked b to one decimal place.
Please first conduct reasoning, and then answer the question and provide the final value, e.g., 1, 2.5, 300, at the end.
Question: At a point during the flight, a plane is 42 kilometres south and 57 kilometres west of the airport it left from.


Find the size of the angle marked b to one decimal place.