For the frame shown (all members 5 m; loads 30 kN at A and 20 kN at C; supported by a pin at E and a cable at D inclined at 30°): (a) find the external forces at D and E; (b) find the forces in members AC and AB. (Bottom chord A–C–E is horizontal with A at the left; B and D are the top joints of equilateral triangles ABC and CDE; the cable at D pulls up and to the right at 30° above the horizontal.)