Two forces of magnitude $8 \,N$ and $15 \,N$ respectively act at a point. If the resultant force is $17 \,N$, the angle between the forces has to be .......
$60$
$45$
$90$
$30$
Two forces $\vec{F}_1$ and $\vec{F}_2$ are acting on a body. One force has magnitude thrice that of the other force and the resultant of the two forces is equal to the force of larger magnitude. The angle between $\vec{F}_1$ and $\overrightarrow{\mathrm{F}}_2$ is $\cos ^{-1}\left(\frac{1}{\mathrm{n}}\right)$. The value of $|\mathrm{n}|$ is__________.
Explain the parallelogram method for vector addition. Also explain that this is comparable to triangle method.
$ABC$ is an equilateral triangle. Length of each side is $a$ and centroid is point $O$. Find If $|\overrightarrow{A B}+\overrightarrow{B C}+\overrightarrow{A C}|=n a$ then $n =$ ?