Solve step by step using legible handwriting, can use python. Explaining the

transformation matrices, and writing the formulas

use the stiffness method, Use principle of linearity and superposition:

It is known $L=2\mathrm{.}5m.$

At node $6$ a force $P=4000kg$ is applied.

At node $5$ a horizontal force of $Q=+3000Kg$ is produced

a$)$ Calculate the stiffness k of bars $6$ and $7$ so that the vertical displacement of node $6$ is

equal to $d_{\text{:}}{?}_{0\mathrm{.}1}$cmi$+0\mathrm{.}5cmj$

The cross section area of bars $1,2,3,4,5,8,9,10,11$ is $0\mathrm{.}02m^2,$ the area of bars $6$ and $7$ is

unknown and the value of $E$ is unknown.

b$)$ Nodal displacements in global coordinates.

c$)$ Global coordinate reactions.

d$)$ Axial force in each element.

e$)$ Axial tension in each bar.