One component of a magnetic field has a magnitude of 0.046 T and points along the +x axis, while the other component has a magnitude of 0.066 T and points along the -y axis. A particle carrying a charge of +7.50*10^-5 C is moving along the +z axis at a speed of 3.20*10^3 m/s.

(a) What is the magnitude of the net magnetic force that acts on the particle?
(b) What is the angle that the net force makes with respect to the +x axis?

Use the magnetic force on a charge equation in two dimensions. If you need, use the right hand rule. I will be happy to critique your thinking.

I figured out the first question using F=Bqvsin90 for X anf Y and then used pythagorean theorem. But I have problems with b, how do I start going about finding the angle? thank you!

The angle with respect to the x axis?

The net force is in the xy plane, so

Theta= arc cos ( x component/magnitude)