MQ≡QN
BQ≡CQ , MBNC patrulater cu diag care se injunmatatesc, MBNC paralelogram
DM≡CQ,⇒MQ||CD⇒MQ⊥BC. MNBC paralelogram d cu diaginale perpendiculare,MBNC romb
b)Arie ABCD=AB² (sau =arie MBNC)
AB=?
MB=Perim:4=24√5:4=6√5
MB=√(AB²+(AB/2)²)= √(5AB²/4)=AB√5/2
AB√5/2=6√5
AB/2=6
AB=12cm
Aria =AB²=12²=144cm²
Altfel
Arie ABCD=arie MBNC= 4Arie ΔABM
cu MB=24√5:4=6√5, tot asa se afla AB=12
atunci MN=2MQ=2AB=2*12=24
Arie romb MBNC=24*12/2=12*12=144cm²
as nice as that!!!
