The proofs and rules discussed in this lesson apply only to the rhombus. Do you know what makes a parallelogram a rhombus, and can you identify a rhombus?

Think about the answer to the first question. A rhombus is a parallelogram with four sides that are the same length. Therefore, the rhombus has all the properties of the parallelogram and the additional property of congruent sides.

Next, practice identifying the rhombus by completing the following activity. Each figure is either a rhombus or a parallelogram. Drag the figure to the appropriate description.

Did you notice that every rhombus is a parallelogram but not every parallelogram is a rhombus? Just remember that a rhombus is a parallelogram with equal sides.