Find unit vector perpendicular to $\vec A$ and $\vec B$ where $\vec A = \hat i - 2\hat j + \hat k$ and $\vec B = \hat i + 2\hat j$

Which of the following quantity/quantities are dependent on the choice of orientation of the co-ordinate axes?

$(a)$ $\vec{a}+\vec{b}$

$(b)$ $3 a_x+2 b_y$

$(c)$ $(\vec{a}+\vec{b}-\vec{c})$

The resultant force of $5 \,N$ and $10 \,N$ can not be ........ $N$

The vectors $5i + 8j$ and $2i + 7j$ are added. The magnitude of the sum of these vector is

Two forces $3\,N$ and $2\, N$ are at an angle $\theta$ such that the resultant is $R$. The first force is now increased to $ 6\,N$ and the resultant become $2R$. The value of is ....... $^o$

Two vectors $\overrightarrow{{X}}$ and $\overrightarrow{{Y}}$ have equal magnitude. The magnitude of $(\overrightarrow{{X}}-\overrightarrow{{Y}})$ is ${n}$ times the magnitude of $(\overrightarrow{{X}}+\overrightarrow{{Y}})$. The angle between $\overrightarrow{{X}}$ and $\overrightarrow{{Y}}$ is -