Vectors in Three Dimensions: Three Forces are concurrent at point $O.$

$5.$ Determine the magnitude of the resultant $\frac{?}{\text{b}\text{a}\text{r}}(R)\frac{?}{b}=ar(F{)}_1\frac{+}{b}ar(F{)}_2\frac{+}{b}ar(F{)}_3.$

a$.26\mathrm{.}2$ kips

b$.25\mathrm{.}1$ kips

c$.23\mathrm{.}9$ kips

d$.22\mathrm{.}2$ kips

$6.$ Select the expression for a unit vector in the direction of $\frac{?}{\text{b}\text{a}\text{r}}(F{)}_2.$

a$.\frac{1}{3}\frac{?}{\text{b}\text{a}\text{r}}(i)+\frac{2}{3}\frac{?}{\text{b}\text{a}\text{r}}(j)+\frac{2}{3}\frac{?}{\text{b}\text{a}\text{r}}(k)$

b$.\frac{2}{3}\frac{?}{\text{b}\text{a}\text{r}}(i)-\frac{2}{3}\frac{?}{\text{b}\text{a}\text{r}}(j)+\frac{1}{3}\frac{?}{\text{b}\text{a}\text{r}}(k)$

c$.\frac{2}{3}\frac{?}{\text{b}\text{a}\text{r}}(i)-\frac{1}{3}\frac{?}{\text{b}\text{a}\text{r}}(j)+\frac{2}{3}\frac{?}{\text{b}\text{a}\text{r}}(k)$

d$.\frac{1}{3}\frac{?}{\text{b}\text{a}\text{r}}(i)-\frac{2}{3}\frac{?}{\text{b}\text{a}\text{r}}(j)+\frac{2}{3}\frac{?}{\text{b}\text{a}\text{r}}(k)$

$7.$ Determine the angle between forces $\frac{?}{\text{b}\text{a}\text{r}}(F{)}_2$ and $\frac{?}{\text{b}\text{a}\text{r}}(F{)}_3.$

a$.104$

b$.91\mathrm{.}0$

C$.99\mathrm{.}0$

d$.95\mathrm{.}0$