Question 18
In the diagram below, $D$ is a point on the line $AC$ such that $BD$ is perpendicular to $AC$. Point $E$ is on the line $BC$ such that $AB$ is parallel to $DE$. The area of triangle $CDE$ is 9 $\mathrm{cm}^2$. Given that $BD=8$ cm and $DC=6$ cm, find the length, in cm, of $AD$.
