Question $6$

Forces of $20,15,30,$ and $50lb$ are concurrent at the origin and are directed through the points whose coordinates are $(2,1,6),$

$(4,-2,5),(-3,-2,1),$ and $(5,1,-2),$ respectively. Determine the angle that the resultant makes with the z$-$axis.

$30\mathrm{.}2$deg

$62\mathrm{.}4$deg

$79\mathrm{.}0$ deg

$46\mathrm{.}4$deg