If $\sin ^{-1} \bigg(\large\frac{3}{x}\bigg)$$+ \sin ^{-1} \bigg(\large\frac{4}{x}\bigg)=\large\frac{\pi}{2}$ then $x=$

Question

$$\begin {array} {1 1} (1)\;3 & \quad (2)\;5 \\ (3)\;7 & \quad (4)\;11 \end {array}$$