Given: Two forces are acting on a flag pole as shown in the figure.

$F_B=320N$ and $F_C=640N$

Find: The magnitude and the coordinate direction angles of the resultant force.

Plan:

Find the forces along $AB$ and $AC$ in the Cartesian vector form.

Add the two forces to get the resultant force, $F_R.$

Determine the magnitude and the coordinate angles of $F_R.$

Vector $F_{AC}$ was solved in class, your job is to compute the force vector $F_{AB}$ in the following figure: