Solve the given questions:
Question I: A long horizontal wire carries 13.0 A of current due north. What is the magnitude of the net magnetic field 19.9 cm due west of the wire if the Earth's field there points downward, 40.0° below the horizontal, and has magnitude 4.74E-5 T?
Question II: Calculate the angle relative to the horizontal with up as the positive direction.
Explain your answers please for best answer for above questions! Thanks.