Three coplanar forces of magnitudes 10 N, 25 N, and 20 N act at a point O in the directions shown in the diagram.

(a) Given that the component of the resultant force in the x-direction is zero, find \(\alpha\), and hence find the magnitude of the resultant force.

(b) Given instead that \(\alpha = 45\), find the magnitude and direction of the resultant of the three forces.