A flat bar ABCDEF of negligible mass is hinged at A and supported by a roller support at D as shown in Figure 4.1. Three external forces are applied at C, E and F respectively. At this position, the flat bar is in equilibrium.

(a) Draw the free body diagram of the flat bar. (b) Determine the magnitude of the reaction at roller support at D. (c) Determine the magnitude and direction of the reaction at A.