648. A _______________ B
D _________________ C
uneste A cu D si B cu C, nu pot face asta
A) AB║ DC
AD ║ BC
b) ab=dc
ad=bc
C) drept. are unghiuri drepte
649. a) AB, BC, CD, DA
b) DAB, ABC, BCD, CDA
c) AB║DC
AD ║BC
