Two vectors \(\overrightarrow{X}\) and \(\overrightarrow{Y}\) have equal magnitude. The magnitude of \((\overrightarrow {X}\text-\overrightarrow{Y})\) is \(n\) times the magnitude of \((\overrightarrow {X}\text+\overrightarrow{Y}).\) The angle between \(\overrightarrow{X}\) and \(\overrightarrow{Y}\) is:
1. \({\cos ^{-1}\left(\dfrac{n^2+1}{n^2-1}\right)} \)
2. \({\cos ^{-1}\left(\dfrac{-n^2-1}{n^2-1}\right)} \)
3. \({\cos ^{-1}\left(\dfrac{n^2-1}{-n^2-1}\right)} \)
4. \({\cos ^{-1}\left(\dfrac{n^2+1}{-n^2-1}\right)} \)