\(h\,=\,15\,cm\)

\(R\,=\,?\)

\(\frac{\sin 90^o}{\sin C}=\mu\)

\(\Rightarrow \quad \sin C=\frac{1}{\mu}=\frac{R}{\sqrt{R^{2}+h^{2}}}=\frac{3}{4}\)

\(\Rightarrow \quad 16 R^{2}=9 R^{2}+9 h^{2}\)

or,   \({7{R^2} = 9{h^2}}\)

or,   \({R = \frac{3}{{\sqrt 7 }}h = \frac{3}{{\sqrt 7 }} \times 15\,\,{\text{cm}}}\)