I1.2 If $\sqrt{b}=\sqrt{8+\sqrt{a}}+\sqrt{8-\sqrt{a}}$, determine the real value of $b$.
\begin{aligned} b & =(\sqrt{8+\sqrt{15}}+\sqrt{8-\sqrt{15}})^{2} \\ & =8+\sqrt{15}+2(\sqrt{8+\sqrt{15}} \cdot \sqrt{8-\sqrt{15}})+8-\sqrt{15} \\ & =16+2 \sqrt{64-15} \\ & =16+2 \sqrt{49} \\ & =16+2 \times 7=30\end{aligned}