I'm having trouble with the algebra of this word problem.

Resultant Force: Find the angle between the forces given the magnitude of their resultant. Force 1 is a vector in the direction of the positive x-axis and force 2 is a vector at an angle theta with the positive x-axis.

Force 1: 45 pounds

Force 2: 60 pounds

Resultant Force: 90 pounds

I'm stuck on solving for the resultant vector component using Force 2's vector component of,

Force 2 = w = 60<cos theta, sin theta>

Would you please write out every step along the way? I really need to learn this so I can pass my test on monday.