Q6: : Block is subject to the three forces shown (F1=?, F2=250 lb, F3=410 lb). Knowing that a = 38°, (a) Determine the required magnitude of the force F1 if the resultant of the three forces is to be vertical. F2 F3 150 102 98 75 ○ 55 F1 (B)Determine the corresponding magnitude of the resultant. * Your answer 3 points 2 points