Link CF
CF=AF
AD=CE
∠FAD=∠FCE
Then △ fad △ FCE
S quadrilateral CDFE = S△FCE+S △FCD
= S△FAD + S△FCD
=S△ACF
=( 1/2)*S△ABC
=( 1/2)*( 1/2) * 8 * 8
= 16