Determine the angular velocity of link BC for the instant indicated. In case (a), the center O

Question:

Determine the angular velocity of link BC for the instant indicated. In case (a), the center O of the disk is a fixed pivot, while in case (b), the disk rolls without slipping on the horizontal surface. In both cases, the disk has clockwise angular velocity w. Neglect the small distance of pin A from the edge of the disk.