Given,

Height of transmitting antenna is, $h_{\mathrm{T}}=50 \mathrm{m}$

Height of receiving antenna is, $h_{\mathrm{R}}=32 \mathrm{m}$

Thus, maximum distance for satisfactory communication will be,

$d_{\mathrm{M}}=\sqrt{2R{h}_{\mathrm{T}}}+\sqrt{2R{h}_{\mathrm{R}}}$ where $R$ is radius of the Earth,

$$\begin{gathered} d_{\mathrm{M}}=\sqrt{2R{h}_{\mathrm{T}}}+\sqrt{2R{h}_{\mathrm{R}}} \\ {d}_{\mathrm{M}}=\sqrt{2\times 64\times {10}^5\times 50}+\sqrt{2\times 64\times {10}^5\times 32} \\ {d}_{\mathrm{M}}=8000\sqrt{10}+6400\sqrt{10} \\ {d}_{\mathrm{M}}=14400\sqrt{10} \mathrm{m} \\ {d}_{\mathrm{M}}=45536.7 \mathrm{m} \\ {d}_{\mathrm{M}}=45.5 \mathrm{km} \end{gathered}$$