Question

Difficulty: MediumArea of Two-Dimensional Shapes

A landscape architect is designing a courtyard in the shape of a right trapezoid. The parallel sides of the courtyard have lengths of 2424 yards and 4040 yards. The side perpendicular to the parallel sides has a length of 1515 yards. A straight path is built from the midpoint of the longer parallel side to the vertex of the shorter parallel side that is adjacent to the perpendicular side, dividing the courtyard into two regions. What is the area, in square yards, of the smaller region?

Answer: 150 square yards

Answer

The area of the smaller region is 150 square yards.
The straight path divides the right trapezoid into two regions: a right triangle and a quadrilateral. The right triangle has a vertical leg of 15 yards (the height of the trapezoid) and a horizontal leg of 20 yards (half of the longer parallel side of 40 yards). The area of this right triangle is 0.5 * 20 * 15 = 150 square yards. The total area of the trapezoid is 0.5 * (24 + 40) * 15 = 480 square yards, making the area of the quadrilateral region 480 - 150 = 330 square yards. Comparing the two regions, the smaller region has an area of 150 square yards.

Step-by-Step Solution

1
Find the length of the segment from the perpendicular corner to the midpoint of the longer parallel side.
20 yards
The midpoint divides the 40-yard side into two equal parts of 20 yards each.
2
Determine the shape and dimensions of the region containing the perpendicular side.
A right triangle with legs of 15 yards and 20 yards.
Since the path goes from the midpoint of the base to the opposite vertex of the perpendicular height, it forms a right triangle with the height and half of the longer base.
3
Calculate the area of this right triangle.
150 square yards
Using the area formula for a triangle, Area = 0.5 * base * height = 0.5 * 20 * 15 = 150.
4
Calculate the total area of the trapezoid and the area of the remaining region to confirm which is smaller.
Total area is 480 square yards; the other region's area is 330 square yards.
The total area is 0.5 * (24 + 40) * 15 = 480. The other region has an area of 480 - 150 = 330. Comparing 150 and 330, 150 is the smaller area.

Key Concept

Area of composite shapes and trapezoids
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