The exercise is taken from linear algebra and its applications, prof. G. Strang
Exercise 2.4.8 Truss
I have already found that: m=n=8 → system is statically determinate, therefore solvable by equilibrium equation.
A is a 8 by 8 square matrix.
Also we know, there aren’t any rigid movements since the truss is fixed. Also, because 8-8 is 0, we're expecting 0 solutions to Au=0
I wrote the forces eq. equilibrium:
$f_{H_1 }=-y_2-y_4 cos30$
$f_{H_2 }=y_2+y_5 cos30$
$f_{H_3 }=-y_7-y_5 cos30$
$f_{H_4 }=y_7+y_4 cos30$
$f_{V_1 }=-y_2-y_4 sin30$
$f_{V_2 }=y_2+y_5 sin30$
$f_{V_3 }=-y_7-y_5 sin30$
$f_{V_4 }=y_7+y_4 sin30$
How should I continue and say something regarding the stability of the system?