I will calculate the area of the farm based on the measurements provided in the field notebook and the scale. The student's work shows a method of dividing the farm into triangles and trapezoids. I will verify these calculations.
First, let's establish the real-world coordinates of the farm's vertices based on the field notebook and the scale 1cm=100 m. The baseline X-Y is 12 cm, which means its real length is 12cm×100m/cm=1200 m.
Let X be at (0,0) and Y be at (1200,0) on the baseline.
The table provides offsets:
- Point A: 200 m from X along the baseline, 100 m offset. Assuming it's below the baseline as per the drawing: A=(200,−100).
- Point B: 250 m from X along the baseline, 950 m offset. Assuming it's above the baseline: B=(250,950).
- Point C: 150 m from Y towards X (so 1200−150=1050 m from X), 1100 m offset. Assuming it's above the baseline: C=(1050,1100).
- Point D: 300 m from Y towards X (so 1200−300=900 m from X), 450 m offset. Assuming it's below the baseline: D=(900,−450).
The area of the farm (polygon A-B-C-D) can be calculated by summing the signed areas of the trapezoids formed by the vertices and their projections onto the baseline.
Area = Area(trapezoid XB′B) + Area(trapezoid B′BCC′) + Area(trapezoid C′CY) + Area(trapezoid YD′D) + Area(trapezoid D′DAA′) + Area(trapezoid A′AX).
Areas above the baseline are positive, and areas below are negative.
Let's calculate each part:
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Area (i): Triangle XB′B
Base XB′=250 m, Height BB′=950 m.
A(i)=21×250m×950m=118750m2
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Area (ii): Trapezoid B′BCC′
Parallel sides BB′=950 m, CC′=1100 m. Height B′C′=1050m−250m=800 m.
A(ii)=21(950m+1100m)×800m=21(2050m)×800m=820000m2
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Area (iii): Triangle C′CY
Base C′Y=1200m−1050m=150 m, Height CC′=1100 m.
A(iii)=21×150m×1100m=82500m2
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Area (iv): Triangle YD′D
Base YD′=1200m−900m=300 m, Height DD′=450 m.
A(iv)=21×300m×450m=67500m2
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Area (v): Trapezoid D′DAA′
Parallel sides DD′=450 m, AA′=100 m. Height A′D′=900m−200m=700 m.
A(v)=21(450m+100m)×700m=21(550m)×700m=192500m2
-
Area (vi): Triangle A′AX
Base A′X=200 m, Height AA′=100 m.
A(vi)=21×200m×100m=10000m2
Now, sum the areas above the baseline and subtract the sum of areas below the baseline.
Areas above baseline: A(i)+A(ii)+A(iii)
Areas below baseline: A(iv)+A(v)+A(vi)
Total Area = (A(i)+A(ii)+A(iii))−(A(iv)+A(v)+A(vi))
Total Area = (118750+820000+82500)−(67500+192500+10000)
Total Area = 1021250m2−270000m2
Total Area = 751250m2
The student's individual calculations are:
A(i) = 67500m2 (This matches my A(iv))
A(ii) = 146250m2 (This does not match any of my calculated areas directly from the table values)
A(iii) = 7500m2 (This does not match)
A(iv) = 31250m2 (This does not match)
A(v) = 18900m2 (This does not match)
A(vi) = 10000m2 (This matches my A(vi))
The student's total area is 451500m2. This indicates that the student used different dimensions for some of the shapes than what is derived from the table. The student's drawing has different dimensions than the table values when converted to the same scale. For example, point A in the table is (200,−100) but in the drawing it is (2cm,−2cm) which means (200,−200).
Given the discrepancy, I will provide the solution based on the table values and the standard method for calculating area from offsets, as this is the most accurate interpretation of the problem statement.
Step 1: Determine the coordinates of the vertices.
Using the scale 1cm=100 m and the baseline X-Y of 12 cm (1200 m):
- A=(200m,−100m)
- B=(250m,950m)
- C=(1050m,1100m)
- D=(900m,−450m)
Step 2: Calculate the areas of the shapes above the baseline.
These are the areas of the trapezoids/triangles formed by points B and C and their projections onto the baseline.
- Area of triangle XB′B:
A1=21×(250m)×(950m)=118750m2
- Area of trapezoid B′BCC′:
A2=21(950m+1100m)×(1050m−250m)=21(2050m)×(800m)=820000m2
- Area of triangle C′CY:
A3=21×(1200m−1050m)×(1100m)=21×(150m)×(1100m)=82500m2
Total area above baseline: Aabove=A1+A2+A3=118750+820000+82500=1021250m2.
Step 3: Calculate the areas of the shapes below the baseline.
These are the areas of the trapezoids/triangles formed by points A and D and their projections onto the baseline.
- Area of triangle XA′A:
A4=21×(200m)×(100m)=10000m2
- Area of trapezoid A′ADD′:
A5=21(100m+450m)×(900m−200m)=21(550m)×(700m)=192500m2
- Area of triangle D′DY:
A6=21×(1200m−900m)×(450m)=21×(300m)×(450m)=67500m2
Total area below baseline: Abelow=A4+A5+A6=10000+192500+67500=270000m2.
Step 4: Calculate the total area of the farm.
The total area of the farm is the sum of the areas above the baseline minus the sum of the areas below the baseline.
Atotal=Aabove−Abelow
Atotal=1021250m2−270000m2
Atotal=751250m2
The total area of the farm is 751250m2.
Tuma swali linalofuata 📸