Diagonals of rhombus are perpendicular area is (1/2)*d1 * d2 where d1 and d2 are the diagonal lengths draw the diagonals on your rhombus and you will see a 30-60-90 triangle and then figure sides will be 6 , 6√3 . 12 so d1 is 2*6 = 12 and d2 is 2*6√3 = 12√3 and area = (1/2)*12*12√3 = 72√3 square cm.