$\begin {array} {1 1} (1)\;sin^{-1} \bigg( \large\frac{1}{\sqrt 3} \bigg) & \quad (2)\;sin^{-1} \bigg( \large\frac{4\sqrt 3}{9} \bigg) \\ (3)\;sin^{-1} \bigg( \large\frac{9\sqrt 3}{16} \bigg) & \quad (4)\;sin^{-1} \bigg( \large\frac{3\sqrt 3}{8} \bigg) \end {array}$