One of the two forces is double and the other resultant is equal to the greater force. The angle between then is

Q. Two forces, with equal magnitude $F$, act on a body and the magnitude of the resultant force is $\frac{F}{3}$. The angle between the two forces is

Q. The angle between the lines $\frac{x}{1}=\frac{y}{0}=\frac{z}{-1}$ and $\frac{x}{3}=\frac{y}{4}=\frac{z}{5}$ is
[Pb. CET 2002]

Q. List I List II
A)
${\sin }^{-1}\left(\frac{1}{2}\right)+{\cos }^{-1}(-\frac{1}{2})$ 1) $\frac{\pi }{2}$
B)
${\sin }^{-1}(-\frac{1}{2})+{\cos }^{-1}\left(\frac{1}{2}\right)$ 2) $\frac{\pi }{6}$

Q. The maximum and minimum of the resultant of two forces are $F$ and $G$ (the angle between these forces is $2\alpha ,$) then, the resultant of $F$ and $G$ is

Q. If $ab<1$ and ${\cos }^{-1}\left(\frac{1-a^2}{1+a^2}\right)+{\cos }^{-1}\left(\frac{1-b^2}{1+b^2}\right)=2{\tan }^{-1}x$, then $x$ is equal to