Chapter $15,$ Problem $82.$

Knowing that at the instant shown bar $AB$ is rotating counterclockwise and that the magnitude of the velocity of the midpoint of bar $BC$ is $7\mathrm{.}8f\frac{t}{s},$ determine $($a$)$ the angular velocity of bar $AB,(b)$ the angular velocity of bar $BC,(c)$ the angular velocity of bar $DC.$

Find: $w_{AB},w_{BC},w_{DC}.|$