Five equal forces of $10 \,N$ each are applied at one point and all are lying in one plane. If the angles between them are equal, the resultant force will be ……….. $\mathrm{N}$

Two forces $P$ and $Q$, of magnitude $2F$ and $3F$, respectively, are at an angle $\theta $ with each other. If the force $Q$ is doubled, then their resultant also gets doubled. Then, the angle $\theta $ is ……. $^o$

The three vectors $\overrightarrow A = 3\hat i – 2\hat j + \hat k,\,\,\overrightarrow B = \hat i – 3\hat j + 5\hat k$ and $\overrightarrow C = 2\hat i + \hat j – 4\hat k$ form

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 ……. $^o$