AB||CD
BC||AD
___________
rezolvare In paraleogramul ABCD avem -
AB||CD
BC||AD
<A = <C
<B=<D
m<a+m<b=180 grade
m<b+m<c=180 grade
m<c+m<d=180 grade
m<d+m<a=180 grade
AO=OC
BO=OD
M<A=90 GRADE
M<B=9O GRADE
M<C= 90 GRADE
M<D=90 GRADE
AC=BD ⇒ABCD Dreptunghi