1. **Problem statement:**
A plot of land has an area of 876 m² and is divided into three rectangular fields of equal width. The total fencing used is 177 m, which includes the perimeter and two internal fences dividing the fields.
2. **Known values:**
- Total area $= 876$ m²
- Height of the plot $= 36$ m
- Width of the plot $= 27$ m (given at the bottom)
- The plot is divided into three fields of equal width, so each field has width $w$ and length $AB$ (unknown).
3. **Find:**
(a) Length $AB$
(b) Perimeter of the plot
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### Step 1: Express the area in terms of $AB$
The total area is given by:
$$\text{Area} = \text{length} \times \text{width}$$
Here, the length is $AB$ and the width is 27 m.
So,
$$AB \times 27 = 876$$
### Step 2: Solve for $AB$
Divide both sides by 27:
$$AB = \frac{876}{27}$$
Calculate:
$$AB = 32.444... \approx 32.44 \text{ m}$$
### Step 3: Find the perimeter of the plot
The perimeter $P$ of a rectangle is:
$$P = 2(\text{length} + \text{width})$$
Using $AB = 32.44$ m and width $= 27$ m:
$$P = 2(32.44 + 27) = 2(59.44) = 118.88 \text{ m}$$
### Step 4: Calculate total fencing used
The fencing includes the perimeter plus two internal fences dividing the plot into three fields.
Each internal fence runs parallel to the length $AB$ and has length $36$ m.
Total fencing:
$$\text{Fencing} = P + 2 \times 36 = 118.88 + 72 = 190.88 \text{ m}$$
But the problem states fencing used is 177 m, so we need to check the width of each field.
### Step 5: Reconsider the width of each field
The plot is divided into three fields of equal width, so each field width is $w$.
Total width is $3w = 27$ m, so
$$w = \frac{27}{3} = 9 \text{ m}$$
### Step 6: Calculate fencing length using $w$ and $AB$
The fencing includes:
- Two lengths of $AB$ (top and bottom)
- Four widths of $36$ m (two sides and two internal fences)
So total fencing:
$$F = 2 \times AB + 4 \times 36$$
Given $F = 177$ m, solve for $AB$:
$$2AB + 144 = 177$$
$$2AB = 33$$
$$AB = 16.5 \text{ m}$$
### Step 7: Verify area with $AB = 16.5$ m and width $27$ m
Area:
$$16.5 \times 27 = 445.5 \text{ m}^2$$
This does not match the given area 876 m², so the width must be different.
### Step 8: Let the width of each field be $w$, so total width is $3w$
Area:
$$AB \times 3w = 876$$
Fencing:
$$2AB + 4 \times 36 = 177$$
From fencing:
$$2AB = 177 - 144 = 33$$
$$AB = 16.5$$
From area:
$$16.5 \times 3w = 876$$
$$3w = \frac{876}{16.5} = 53.09$$
$$w = \frac{53.09}{3} = 17.7$$
### Step 9: Final answers
(a) Length $AB = 16.5$ m
(b) Perimeter $P = 2(AB + 3w) = 2(16.5 + 53.09) = 2(69.59) = 139.18$ m
Plot Length 81B1E0
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