Răspuns:
Explicație pas cu pas:
ΔADC este echilateral Aadc=AD²√3/4=121√3/4 cm²
in trapez ducem DE⊥AB
In ΔADE AD=11cm AE=(AB-CD)/2=11/2=5,5cm,
AD⇒/AE=2 ⇒∡ADE=30° ⇒DE=AEcos30°=11√3/2=5,5√3 cm
Aabcd=((Ab+CD)xDE/2=(22+11)×5,5√3=33×5,5√3 cm²
Aadc/Aabcd=121√3/4×1/33x5,5√3=11/3x11/2=1/6