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 -
$\cos ^{-1}\left(\frac{n^{2}+1}{n^{2}-1}\right)$
$\cos ^{-1}\left(\frac{{n}^{2}-1}{-{n}^{2}-1}\right)$
$\cos ^{-1}\left(\frac{-n^{2}-1}{n^{2}-1}\right)$
$\cos ^{-1}\left(\frac{n^{2}+1}{n^{2}-1}\right)$
Given that $\overrightarrow A + \overrightarrow B + \overrightarrow C= 0$ out of three vectors two are equal in magnitude and the magnitude of third vector is $\sqrt 2 $ times that of either of the two having equal magnitude. Then the angles between vectors are given by
Two forces of magnitude $3\;N$ and $4\;N $ respectively are acting on a body. Calculate the resultant force if the angle between them is $0^o$
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 ....... $^o$
Two forces are such that the sum of their magnitudes is $18\; N$ and their resultant is $12\; N$ which is perpendicular to the smaller force. Then the magnitudes of the forces are