The problem is as follows:
The figure from below shows a set of vectors. Find the unit vector of $\vec{A}+\vec{B}$ as a function of the unit vectors $\vec{u_1}$ and $\vec{u_2}$. It is known that the sides of the rhombus is $6$.
The alternatives given are as follows:
$\begin{array}{ll} 1.&\frac{(3\vec{u_1}+\vec{u_2})}{\sqrt{10}}\\ 2.&\frac{(3\vec{u_1}+\vec{u_2})}{\sqrt{13}}\\ 3.&\frac{(3\vec{u_1}-\vec{u_2})}{\sqrt{10}}\\ 4.&\frac{(3\vec{u_1}-\vec{u_2})}{\sqrt{7}}\\ 5.&\frac{(3\vec{u_1}-\vec{u_2})}{\sqrt{13}}\\ \end{array}$
I'm totally lost at this problem exactly how to find the resultant. The information regarding the sides of the rhombus it is a little bit ambiguous to me as it is stated. Does it mean that the sum of all sides is $6$ or each side is $6$?. How should I made the interpretation?. Because if it is meant $4x=6$ then $x=\frac{3}{2}$. But if it meant that each side is $6$. then $\left\|\vec{B}\right\|=6$ and $\left\|\vec{A}\right\|=3$.
Can somebody help me here?.