$[14]4.$ A single crank drive mechanism of a press is shown in the sketch. The crank length $\backslash ($ r $\backslash )$ is $10$ in and the$\_$connecting bar AB is $30$ in $.$ When the velocity of the plunger B is $\backslash (85\backslash$mathrm$\{$in$\}/\backslash$mathrm$\{$s$\}\backslash )$ toward left and the angle $\backslash (\backslash$varphi $\backslash )$ is $15$ degrees, determine a$)$ the angular velocity of the connecting bar AB and; b$)$ the velocity of point A$.($Use either the IC approach or Cartesian coordinate vector analysis approach for solving the problem$)$