Răspuns:
Explicație pas cu pas:
Aria(ABCD)=AD·(AB+CD)/2, CD=4√3cm=AH.
In ΔBCH, deoarece ∡B=30°, ⇒CH=(1/2)·BC=(1/2)·8=4cm=AD
Atunci BH²=BC²-CH²=8²-4²=(8-4)(8+4)=4·4·3, deci BH=√(4·4·3)=2·2·√3=4√3cm, deci AB=AH+BH=4√3+4√3=8√3cm
Atunci Aria(ABCD)=AD·(AB+CD)/2=4·(8√3+4√3)/2=2·12√3=24√3cm².