Question

If x = 7 units, y = 2 units, and h = 9 units, find the area of the trapezoid shown above using decomposition.

A.
81 square units
B.
99 square units
C.
63 square units
D.
72 square units

Answer 1

A) 81 sq units

Explanation:

Area of a trapezoid = one-half of height multiplied by the sum of the bases (the bases are the parallel sides)

the problem gives us all the values we need:

height = 9

smaller base is 'x' which is 7

larger bases is 2y+x which is 2(2)+7 = 11

A = 1/2·(9)(7+11)

= 1/2·9·18

= 9·9 which is 81 sq units