<PRE><B>Question 1168410</B>
.


For the Earth conditions, &amp;nbsp;the correct formula is


    &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;d = {{{1.22459*sqrt(h)}}} &amp;nbsp;&amp;nbsp;miles,  &amp;nbsp;&amp;nbsp;with &amp;nbsp;h &amp;nbsp;in feet.



See, &amp;nbsp;for example, &amp;nbsp;this source


&lt;A HREF=https://sites.math.washington.edu/~conroy/m120-general/horizon.pdf&gt;https://sites.math.washington.edu/~conroy/m120-general/horizon.pdf&lt;/A&gt;


https://sites.math.washington.edu/~conroy/m120-general/horizon.pdf



</PRE>