Find the area of a rhombus with side length 6 and an interior angle with measure 120°.

One way to find the area of a parallelogram is the use the formula:  Area  =  (a)(b)(sin(C))

where  a  and  b  are the lengths of two adjacent sides and  C  is the size of the included angle.

Since a rhombus is a parallelogram:  a = 6,  b = 6,  and  C = 120^o .

Area  =  (6)(6)(sin(120))  =  31.18  (approximately)