An L-shaped reinforced concrete slab 12 ft ×12 ft (but with a 6 ft × 6 ft cutout) and thickness t = 9.0 in. is lifted by three cables attached at O, B and D, as shown in the figure. The cables are combined at point Q, which is 7.0 ft above the top of the slab and directly above the center of mass at C. Each cable has an effective crosssectional area of Ae = 0.12 in2.
(a) Find the tensile force Ti (i = 1, 2, 3) in each cable due to the weight W of the concrete slab (ignore weight of cables).
(b) Find the average stress σi in each cable. (See Table H-1 in Appendix H for the weight density of reinforced concrete.)

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Coordinates of D in ft (5, 5, 7 D (5, 12, 0) Ti T7 C(5, 5,0) 7 6 ft (0,0.0 * 6 ft B (12, 0, 0) lb Concrete slab γ= 150 Thickness t, c.g at (5 ft, 5 ft, 0)