First, let's calculate the height to the top of the building:
Thereby,
[tex]\begin{gathered} \tan 39=\frac{B}{58}\rightarrow B=58\tan 39 \\ \Rightarrow B=46.97m \end{gathered}[/tex]Now, let's calculate the height to the top of the radio tower:
This way,
[tex]\begin{gathered} \tan 48=\frac{T}{58}\rightarrow T=58\tan 48 \\ \Rightarrow T=64.42 \end{gathered}[/tex]Substracting both heights, we'll get that:
[tex]64.42-46.97=17.45[/tex]The radio tower is 17.45 m tall.