All forces are resolved in two perpendicular axes (X and Y) as shown in the figure.
Since, block of mass m is in equilibrium. Hence, resolving the forces in x -direction, we get |F2|‌cos(60∘)=|F1|cos(30∘) |F2|×‌
1
2
=10×‌
√3
2
‌‌(∵|F1|=10N‌ given ‌) |F2|=10√3N Again, resolving the force in y -direction, we get |F3|‌‌=|F1|sin(30∘)+|F2|sin(60∘) ‌‌=10×‌