Rhombus
A rhombus is a parallelogram with four congruent sides. The plural of rhombus is rhombi. (I love that word.)
The formula for the area of a rhombus is the same as the formula for a parallelogram:
A = bh,
where b is the length of a base and h is the height.
Area = 5 · 4 = 20 cm2.
