Two forces acting on point $A$ along their side and having magnitude reciprocal to length of side then resultant of these forces will be proportional to

Two forces, ${F_1}$ and ${F_2}$ are acting on a body. One force is double that of the other force and the resultant is equal to the greater force. Then the angle between the two forces is

$\overrightarrow{ A }=4 \hat{ i }+3 \hat{ j }$ and $\overrightarrow{ B }=4 \hat{ i }+2 \hat{ j }$. Find a vector parallel to $\overrightarrow{ A }$ but has magnitude five times that of $\vec{B}$.

The vector sum of two forces is perpendicular to their vector differences. In that case, the forces

How many minimum number of non-zero vectors in different planes can be added to give zero resultant

The five sides of a regular pentagon are represented by vectors $A _1, A _2, A _3, A _4$ and $A _5$, in cyclic order as shown below. Corresponding vertices are represented by $B _1, B _2, B _3, B _4$ and $B _5$, drawn from the centre of the pentagon.Then, $B _2+ B _3+ B _4+ B _5$ is equal to