Question

Demonstrati ca este un paralelogram,cel cu roșu!!!

Answer 1

In ∆ACD
Q->mij.AC}
M->mij.AD} =>QM-->linie mijlocie =>QM ll CD
In ∆BCD
N->mij.BC}
P->mij. BD} =>NP->linie mijlocie =>NP ll CD
QM ll CD}
NP ll CD} =>QM ll NP (1)

In ∆CAB
Q->mijloc AC}
N->mijloc BC} =>QN->linie mijlocie=>QN ll AB
In ∆DAB
M-->mij. AD}
P->mij. BD} =>MP->linie mijlocie=> MP ll AB
QN ll AB}
MP ll AB} => QN ll MP (2)
(1)}
(2)} => MPNQ este paralelogram