A ball suspended by a thread swings in a vertical plane so that its magnitude of acceleration in the extreme position and lowest position are equal. The angle \(( \theta) \) of thread deflection in the extreme position will be:
\(\displaystyle 2 \tan^{-1}\!\left(\frac{1}{\sqrt{5}}\right) \)
\(\displaystyle 2 \tan^{-1}\!\left(\frac{1}{2}\right) \)
\(\displaystyle \tan^{-1}\!\left(\frac{1}{2}\right) \)
\(\displaystyle \tan^{-1}\!\left(\sqrt{2}\right) \)