Explicație pas cu pas:
a) P-mij. CN
M-mij. BC
=> PM linie mij. in triunghiul BCN => PM=BN/2=>BN=2PM
b) AN/AB=1/3=>AN/NB=1/2
mB=30=>( T.30.60.90) BC=2AC => AC/BC=1/2
=>AN/NB=AC/BC => (R.T.B ) CN bisectoarea C
Fie CNnAM={O} =< CO_|_AM <=> PO_|_AM<=>PN_|_AM
PM=NB/2=> PM=AN (AN/NB=1/2)
PM//AN
=> APMN paralelogram dar PN_|_AM => APMN romb
