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 find the total area of the garden plot, we can treat the coordinates of the poles as vertices of a quadrilateral. We will calculate the area using the Shoelace Formula, which is suitable for polygons defined by their vertices.

The Shoelace Formula

For a quadrilateral with vertices (x1,y1),(x2,y2),(x3,y3),(x4,y4)(x_1, y_1), (x_2, y_2), (x_3, y_3), (x_4, y_4), the area is given by:

Area=12x1y2+x2y3+x3y4+x4y1(y1x2+y2x3+y3x4+y4x1)\text{Area} = \frac{1}{2} \left| x_1y_2 + x_2y_3 + x_3y_4 + x_4y_1 - (y_1x_2 + y_2x_3 + y_3x_4 + y_4x_1) \right|

Step 1: Write the Coordinates in Order

The vertices are:

  • (0,0)(0, 0)
  • (6,0)(6, 0)
  • (4,5)(4, 5)
  • (2,4)(2, 4)

We list them in the correct order (clockwise or counterclockwise). The vertices in clockwise order are: (0,0)(6,0)(4,5)(2,4)(0, 0) \to (6, 0) \to (4, 5) \to (2, 4)

Step 2: Apply the Shoelace Formula

Substitute the values into the formula:

Area=1200+65+44+20(06+04+52+40)\text{Area} = \frac{1}{2} \left| 0 \cdot 0 + 6 \cdot 5 + 4 \cdot 4 + 2 \cdot 0 - (0 \cdot 6 + 0 \cdot 4 + 5 \cdot 2 + 4 \cdot 0) \right|

Simplify step by step:

  1. Calculate the first term: 00+65+44+20=0+30+16+0=460 \cdot 0 + 6 \cdot 5 + 4 \cdot 4 + 2 \cdot 0 = 0 + 30 + 16 + 0 = 46

  2. Calculate the second term: 06+04+52+40=0+0+10+0=100 \cdot 6 + 0 \cdot 4 + 5 \cdot 2 + 4 \cdot 0 = 0 + 0 + 10 + 0 = 10

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

  4. Take the absolute value and divide by 2: Area=1236=18\text{Area} = \frac{1}{2} \cdot 36 = 18

Final Answer:

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

Would you like a breakdown of any specific steps, or have additional questions?


  1. What is the Shoelace Formula, and how does it apply to polygons?
  2. How can you determine the correct order of vertices for a quadrilateral?
  3. What happens if you list the vertices in the wrong order?
  4. How would the calculation differ for a non-convex quadrilateral?
  5. Can the Shoelace Formula be used for polygons with more than 4 sides?

Tip: Always ensure vertices are listed in the correct sequential order (clockwise or counterclockwise) for accurate area calculations.

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Math Problem Analysis

Mathematical Concepts

Geometry
Coordinate Geometry
Polygon Area Calculation

Formulas

Shoelace Formula for polygon area

Theorems

Shoelace Theorem

Suitable Grade Level

Grades 9-12