Rombul:     paralelogramul ce are doua laturi consecutive congruente.

                                                                                                                                     

          

                                                                                                                         - diagonala mica

                                                                                                                                      - diagonala mare

 

Aria :                                          ;

 

Perimetrul :                                   

 

Teoreme:

                                                        - toate laturile rombului sunt congruente.

                                                        - intr-un romb diagonalele sunt perpendiculare intre ele si sunt bisectoarele unghiurilor lor.