Balok ABCD EFGH, AB=24cm, BC=18cm  dan  AE=16cm  luas bidang diagonal BDHF adalah?

AB=24 cm
AD=BC=18 cm
BD = 3 4 5 (pake tripel phytagoras)
18 24 (30)
BF=AE=16 cm
luas BDHF= BD × BF = 30 cm × 16 cm
= 480 cm kuadrat