Răspuns :
EM = NF = GP = HQ =>
=> MF = NG = PH = QE =>
=> ΔMFN = ΔNGP = ΔPHQ = ΔQEM =>
=> MN = NP = PQ = QM => MNPQ = romb (1)
∡QMN = 180° - (∡EMQ+∡MFN) } => ∡QMN = 90° (2)
∡EMQ+∡MFN
Din (1) si (2) => MNPQ = patrat
EM = NF = GP = HQ =>
=> MF = NG = PH = QE =>
=> ΔMFN = ΔNGP = ΔPHQ = ΔQEM =>
=> MN = NP = PQ = QM => MNPQ = romb (1)
∡QMN = 180° - (∡EMQ+∡MFN) } => ∡QMN = 90° (2)
∡EMQ+∡MFN
Din (1) si (2) => MNPQ = patrat