$2)$ At the instant given, it is known that the angular velocity of rod $\backslash ($ A B $\backslash )$ is $\backslash (20\backslash$mathrm$\{$rad$\}/\backslash$mathrm$\{$s$\}\backslash )$ clockwise. By use of Cartesian vector form, determine $($a$)$ the angular velocity of rod BD$,($b$)$ the velocity of the point $\backslash ($ D $\backslash ).$