**The diagonals of a rhombus have 3 properties that we can use without having to prove them:**

- The diagonals of a rhombus intersect. (not only do they intersect, but they do so exactly at the midpoint of each one).
- The diagonals of a rhombus are perpendicular, forming a right angle of $90^o$ degrees.
- The diagonals of a rhombus cross the angles of the rhombus.

**The diagonals of a rhombus have 2 properties that we must prove to use them:**

- The diagonals of a rhombus form four congruent triangles.
- The diagonals of a rhombus create equal alternate angles.

**Other properties:**

- The lengths of the diagonals of a rhombus are not equal.

**The product of the diagonals divided by 2 is equal to the area of the rhombus:**

$\frac{product~of~the~diagonals}{2}=area~of~rhombus$