In the right angled triangle $ABC$, $\angle A = 90^\circ$, $AB=8$, $AC=6$, $BC = 10$. $D$ is a point on $AB$ in such way that if a perpendicular $DE$ is drawn on $BC$ from $D$ then $BE = 4$. What is the area of the quadrilateral $ADEC$?
Source: Bangladesh Math Olympiad 2015 junior category.
I can not find any way to solve this math. Can anyone give me a hint?