[ANSWERED] 1. Derive Eq. (3.7.21) for stress in space truss elements by a process similar to that used to…

1. Derive Eq. (3.7.21) for stress in space truss elements by
a process similar to that used to derive Eq. (3.5.6) for stress in a plane
truss element.
2. For the truss shown in Figure P3–46, use symmetry to
determine the displacements of the nodes and the stresses in each element. All
elements have E = 30 10
6
psi. Elements 1, 2, 4, and 5 have A = 10 in
2
and element 3 has A = 20 in
2
.