Motion of a particle in a magnetic field.

The only force acting on a particle with charge e and velocity **v**, in a constant magnetic field **B**, is e**v** × **B**. Also, **r**(0)=0 and .

I've shown that:

.

Now the question asks to find equations for the path of the particle if **B**=(B,0,0) , **V**=(v_1,v_2,0) and **r**=(x,y,z).

I evaluated the cross product and equated the components to get:

By solving the second and third equations, I generate equations involving exponentials but the answer has equations involving sin and cos.

Can someone see where I've gone wrong? Thanks in advance.