The flywheel turns clockwise with a constant speed of 670 rev/min, and the connecting

The flywheel turns clockwise with a constant speed of 670 rev/min, and the connecting rod ab slides through the pivoted collar at c. for the position θ = 57°, determine the angular velocity ωab (positive if counterclockwise, negative if clockwise) of ab by using the relative-velocity relations. (suggestion: choose a point d on ab coincident with c as a reference point whose direction of velocity is known.)