Problem $3.(30$ Points$)$

A four$-$bar mechanism, with dimension as shown in figure is driven by crank $2$ at a

constant angular speed of ${}_2=600rpm$ in CCW$.$

Find the instantaneous velocities of coupler point $P$ and angular velocities of links $3$

and $4$ in the position shown.

Scale, Space diagram: $1cm$:$7\mathrm{.}5cm$

Velocity polygon: $1cm$:$148c\frac{m}{s}$