Question $1$: Consider the simple truss system $($frame$)$ given below. The stress $$ in both members $AB$ and $BC$ is to be the same. Determine the angle $$ necessary to achieve the minimum weight of construction. Members $AB$ and $BC$ have constant cross$-$section.

Hint: The weight $W$ of the frame can be calculated using:

$W=(A_{BC}L+A_{AB}\frac{L}{cos()})$

where $$ is the weight per unit volume.