$50\%$ Part $($a$)$ Determine the direction of the force on $q($with $q>0)$ in the figure, given that $q_a=q_b=+7\mathrm{.}50C$ and $q_c=q_d=-7\mathrm{.}50C.$

Straight downward

$50\%$ Part $($b$)$ Calculate the magnitude of the force on the charge $q$ in newtons, given that the square is $7cm$ on a side and $q=1\mathrm{.}75C.$

$F=|$