FIGURE P$17\mathrm{.}36/37$Determine the vertical displacement of joint D for the

truss shown in Figure P$17\mathrm{.}36/37.$ Assume that each member has

a cross$-$sectional area A $=1\mathrm{.}60$ in$\mathrm{.}2$ and an elastic modulus

E $=29,000$ ksi. The loads acting on the truss are P $=20$ kips and

Q $=30$ kips