Given the posture of link $2,$ the problem is to define the postures of links $3$ and $4$ and the position of coupler point P $.$

Given: $AO=20mm,OC=50mm,BC=25mm,AB=60mm,AP=40mm,{}_2=100,=30$

Solve: A$\text{'}$s position and $R_{BA}$; B$\text{'}$s position and $R_{BC}$; P$\text{'}$s position

Solve it using the graphical method only. It should be noted that B has two possible positions.