Find the length of the shadow on the ground of a pole of height $\displaystyle 18$ m when angle of elevation $\displaystyle \theta$ of the sun is such that $\displaystyle \tan \theta=\frac{6}{7}$.

Pole of height $\displaystyle \mathrm{AB}=18 \mathrm{~m}$ AP = length of shadow In $\displaystyle \triangle \mathrm{APB}, \tan \theta=\frac{18}{A P}$ \[\begin{aligned} \frac{6}{7} & =\frac{18}{A P} \\ \Rightarrow \mathrm{AP} & =21 \mathrm{~m} \end{aligned} \]