Răspuns:
a)Diagonalele paralelogramului se înjumtasesc =>AC=15 CM•2=30CM,BD=20 CM •2=40CM,AC+BD=30 CM+40 CM =70 CM
b)AO=20CM
OB=2 supra 5•AO
OB=8CM
BD=OB•2
BD=16CM
AC=AO•2
AC=20•2=40CM
AC+BD=16 CM+40CM=56CM
c)OA=10CM
AC=OA•2=20CM
OD=1supra 5 +AO
OD=1 supra 5+10 CM
5 OD=15 CM
OD=3CM
BD =OD•2. =6CM
AC+BD=20CM+6CM=26CM
d)CD=8CM
P AOB=23 CM
DC=8CM=>DO+OC=23CM-8CM=15CM=>AC+BD=15 CM•2=30CM
