$($I$)$ Use the principle of complementary virtual work to determine the forces in each of the three springs connected in series depicted in fig. $9\mathrm{.}39.(2)$ Find the solution of the same problem using the force method developed in section $4\mathrm{.}3\mathrm{.}3.(3)$ Compare the two solution approaches.

Fig. $9\mathrm{.}39.$ Three$-$spring hyperstatic system.