Compare the magnitude of the axial force computed for member (2):

$\left|{\mathrm{F}}_2\right|=398.6 \mathrm{kN}$

with the allowable axial force:

${\mathrm{F}}_{2,\mathrm{allow}}=348.75 \mathrm{kN}$

Since the computed force is greater than the allowable force for member (2), it is now evident that our original assumption was incorrect. The force in member (2) is actually the key consideration which dictates the allowable maximum load $\mathrm{P}$ that can be supported by the structure.