The rhombus is the parallelogram with two consecutive congruent sides.
Because the rhombus is a particular parallelogram, all the properties of the parallelogram are also valid for the rhombus.
- all sides are congruent;
- the diagonals are (reciprocally) perpendicular;
- diagonals are also bisectors of angles;
- the perimeter is four times the side;
- the area is equal to half the product of the diagonals;
- the area is four times larger than the area of the right triangle formed by one side and the two half-diagonals.
- the opposite sides are parallel and congruent;
- opposite angles are congruent (equal), adjacent angles are supplementary;
- the diagonals are cut into congruent segments (“halved”);
- the area is equal to twice the area of the triangle formed by two adjacent sides and the diagonal opposite them.