7)
tg <ABD=AD/AB=1/4
Daca o este ontersectia diagonalelor si
Daca M∈AD, si DM=MA M= mijlocul lui AD ⇒MO=1/2*AB
Comparam ΔDMO cu ΔDAB
MO=1/2AB
MD=1/2AD
OD=1/2BD
<DMO=<DAB=90
⇒ΔDMO ≡ΔDAB
DM/MO=AD/AB=1/4
8)in ΔABD
4AD=AB
BD²=AB²+AD²
17²=AD²+16AD²=17AD²
AD²=17
AD=√17=>
AB=DC=4*√17
Aria MOC=Aria MOD+Ari DOC-Aria MDC
Aria MOD=MO*MD/2=(4√17/2*√17/2):2=17/2
Aria DOC=DC*MD/2=4√17*√17/2*1/2=17
Aria MDC=MD*DC/2=√17/2*4√17/2=17
Aria MOC=17/2+17-17=17/2
