Math Problem Statement

A gardener marks out a garden plot with poles positioned at specific locations: the first pole is at (0,0), the second pole is 6 feet to the east at (6,0), the third pole is at (4,5), and the fourth pole is at (2,4). Calculate the total area of the garden plot.

Solution

To calculate the area of the garden plot, we can use the Shoelace Theorem (also known as Gauss's area formula). This formula helps us find the area of a polygon when the vertices are given as coordinates.

Coordinates of the poles:

  1. First pole: (0,0)(0, 0)
  2. Second pole: (6,0)(6, 0)
  3. Third pole: (4,5)(4, 5)
  4. Fourth pole: (2,4)(2, 4)

The Shoelace Theorem states that if the vertices of the polygon are given by (x1,y1),(x2,y2),,(xn,yn)(x_1, y_1), (x_2, y_2), \dots, (x_n, y_n), the area is calculated as:

A=12i=1n1(xiyi+1yixi+1)+(xny1ynx1)A = \frac{1}{2} \left| \sum_{i=1}^{n-1} (x_i \cdot y_{i+1} - y_i \cdot x_{i+1}) + (x_n \cdot y_1 - y_n \cdot x_1) \right|

Let's apply the coordinates of the garden plot to this formula.

Step-by-step calculation:

  1. Write the coordinates, repeating the first coordinate at the end to close the loop: (0,0),(6,0),(4,5),(2,4),(0,0)(0, 0), (6, 0), (4, 5), (2, 4), (0, 0)

  2. Multiply the coordinates in a specific order (cross-multiplication): Sum 1=(0×0)+(6×5)+(4×4)+(2×0)=0+30+16+0=46\text{Sum 1} = (0 \times 0) + (6 \times 5) + (4 \times 4) + (2 \times 0) = 0 + 30 + 16 + 0 = 46 Sum 2=(0×6)+(0×4)+(5×2)+(4×0)=0+0+10+0=10\text{Sum 2} = (0 \times 6) + (0 \times 4) + (5 \times 2) + (4 \times 0) = 0 + 0 + 10 + 0 = 10

  3. Subtract the second sum from the first sum: 4610=3646 - 10 = 36

  4. Now, divide by 2 to get the area: A=12×36=18A = \frac{1}{2} \times 36 = 18

Conclusion:

The total area of the garden plot is 18 square feet.


Would you like further details on the Shoelace Theorem or have any questions about this problem?

Here are some related questions:

  1. How do you apply the Shoelace Theorem to a triangle?
  2. What if the coordinates were in a different order?
  3. Can the Shoelace Theorem be used for irregular polygons?
  4. How do you calculate the area of a garden plot if it has more than four poles?
  5. Can you use the Shoelace Theorem for three-dimensional shapes?

Tip: Double-check the coordinates to ensure you close the loop (i.e., repeat the first point as the last one).

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Math Problem Analysis

Mathematical Concepts

Geometry
Area of Polygons
Coordinate Geometry

Formulas

Shoelace Theorem (Gauss's Area Formula): A = 1/2 |Σ (x_i * y_(i+1) - y_i * x_(i+1)) + (x_n * y_1 - y_n * x_1)|

Theorems

Shoelace Theorem

Suitable Grade Level

Grades 9-12