3/56 Determine the external reactions at A and F for the roof truss loaded as shown. The vertical loads repre- sent the effect of the supported roofing materials, while the 400-N force represents a wind load. 500 N 500 N 400 N S 60° 8.500 N D B 129 الو 250 N E 250 N 30 30 60° 30° 30° 30° F A G 10 m-