Solution.
Let the height of the tree be h
[tex]\begin{gathered} Using\text{ the idea of similar triangle,} \\ \frac{4}{9}=\frac{h}{9+12} \end{gathered}[/tex][tex]\begin{gathered} \frac{4}{9}=\frac{h}{21} \\ h=\frac{21\text{ x }4}{9} \\ h=\frac{28}{3} \\ h=9\frac{1}{3}\text{ ft} \end{gathered}[/tex][tex]The\text{ height of the tree is 9 }\frac{1}{3}\text{ ft}[/tex]
The correct option is C
