$(25\%)$ You are looking for the internal forces in the following truss, which represents the roof frame

of a house. Use the knot method you learned in first$-$year mechanics to develop two systems of

$($a$)$ Find the internal forces $(vec(x))$ by multiplying the inverse of the coefficient matrix $([A{]}^{-1})$ and the

vector of known external forces $(vec(B))$ for the two load combinations. $($Use Excel for this

question$).$

$($b$)$ Compare the result of the two load combinations and indicate the maximum forces in each

element of the truss.

Dead load $=D=10kN$

This is optional

Wind load $=W=6+x**kN$

Snow load $=S=12kN$

$x^{**}=0$