Particle is at rest, a = 0.
So, resultant force due to all forces will be zero.
F2 = \(\frac{F_3+F_4}{\sqrt{2}}\) = \(\frac{2+1}{\sqrt{2}}\) = \(\frac{3}{\sqrt{2}}N\)
\(F_1+\frac{F_3}{\sqrt{2}}\) = \(\frac{F_4}{\sqrt{2}}\)
F1 = \(\frac{F_4-F_3}{\sqrt{2}}\) = \(\frac{1}{\sqrt{2}}N\)