Step-by-step explanation:
We know that
[tex]tan\theta =\frac{altitude}{base}[/tex]
Using this for the triangles
For the small triangle
[tex]tan \theta =\frac{6\frac{1}{2} }{9}[/tex]
[tex]\Leftrightarrow tan \theta =\frac{\frac{13}{2} }{9}[/tex]
[tex]\Leftrightarrow tan \theta =\frac{13} {18}[/tex]
Again for the bigger triangle
[tex]tan \theta =\frac{h}{31\frac{1}{2} }[/tex]
[tex]\Leftrightarrow tan \theta =\frac{h}{\frac{63}{2} }[/tex]
[tex]\Leftrightarrow tan \theta =\frac{2h}{63}[/tex]
Therefore
[tex]\frac{2h}{63} =\frac{13}{18}[/tex]
[tex]\Leftrightarrow h=\frac{13 \times 63}{18 \times 2}[/tex]
[tex]\Leftrightarrow h=\frac{819}{36}[/tex]
[tex]\Leftrightarrow h = 22.75[/tex] ft
Therefore h = 22.75 ft