Looking at the figure, we can tell that the top is a triangle and the base is a trapezium. To find the area of the figure, we would find the sum of the triangle and the trapezium.
Recall, the formula for finding the area of a triangle is expressed as
Area = 1/2 x base x height
Looking at the triangle,
base = 9 + 9 = 18
height = 3
Thus, Area = 1/2 x 18 x 3 = 27
Again, the formula for finding the area of a trapezium is expressed as
Area = 1/2(a + b)h
where
h is the height of the trapezium
a and b are the lengths of the parallel sides
Looking at the trapezium,
a = 9 + 9 = 18
b = 13.4 + 13.4 = 26.8
h = 12
Area = 1/2(18 + 26.8)12
Area = 268.8
rounding to the nearest whole number,
Area = 269 squared ft