Depending on which of Exercises 7 through 12 you have completed, determine the required crosssectional areas of the members comprising one or more of the following structures. Assume steel members with a factor of safety of N = 3.0, a yield strength of S_Y = 36. × 10⁶ lbf/in² (or 250 MPa), and an elastic modulus of E = 29. × 10⁶ lbf/in² (or 200 GPa). Also assume square cross sections, and consider buckling.

a. The truss in Exercise 7.

b. The truss in Exercise 8.

c. The truss in Exercise 9.

d. The truss in Exercise 10.

e. The truss in Exercise 11.

f. The truss in Exercise 12.