The formula for determining the area of a trapezoid is expressed as
Area = 1/2(a + b)h
where
a and b are the length of the opposite sides of the trapezium
h is the height
From the information given,
a = 21
b = 9
h = 5
Area = 1/2(21 + 9)5 = 1/2(30)5
Area = 75 square feet
The area of a rectangle is expressed as
Area = length x width
Given that the rectangle and the trapezoid has the same area, it means that
75 = 5 x l
l = 75/5
l = 15
Thus, length of the rectangle is 15 ft
