A particle P is acted by three coplanar forces as shown in the figure.Find the force needed to prevent the particle P from moving. (take 3 = 1.7)

Let applied force is F4 = Fx i^+Fyj^To prevent the particle P from moving, net force on the particle will be zero.∴    ∑ Fx = 0or ∑ Fx =Fx+150+200cos300 = 0∴ Fx = -150-1003 = -(150+170) = -320 N and ∑ Fy = 0or 200 sin300 - 100+Fy  = 0  ∴  Fx = 0It means F4 is direction opposite to F1.