The height of the rhombus is 12 in. We get this answer by dividing the area by the base which is 216 / 18. 216 / 18 equals 12, so we have our answer of 12 inches.
There are 10 feet of posts on each side. That means there are 40 feet of fencing in total. If you divide that by two (to represent posts being 2 feet apart) then you get 20. There are 20 posts needed.
