In Δ ABD :
AD²= BD²-AB²
AD² = 36-16
AD²=20
AD = BC = 2√5
AE×BD = AB×AD (a 2-a teorema a inaltimii)
AE = AB×AD / BD = 4×2√5 / 6 = 4√5/3
In Δ DBC :
sin < B = CD / BD = 4/6 = 2/3
P ABCD = 2(4+2√5) = 8 +4√5
In Δ ABE :
BE²=AB²-AE²
BE²= 16 - 80/9
BE²= 144/9
BE = 12/3 = 4
DE = BD-BE= 6-4 = 2
