Convert the cm to feet for the base and the height:
12/2 = 6 x 3 = 18 feet
9/2 = 4.5 x 3 = 13.5 feet
area = 1/2 x base x height
Area = 1/2 x 18 x 13.5
Area = 121.5 square feet
answer: 121.5 square feet
