Complete the table for the four rectangles. Find each missing side length, perimeter, or area.
<table>
<tr><th>Rectangle</th><th>Length \(l\)</th><th>Width \(w\)</th><th>Perimeter \(P\)</th><th>Area \(A\)</th></tr>
<tr><td>1</td><td>\(12\,\text{cm}\)</td><td></td><td></td><td>\(96\,\text{cm}^2\)</td></tr>
<tr><td>2</td><td>\(25\,\text{m}\)</td><td></td><td>\(140\,\text{m}\)</td><td></td></tr>
<tr><td>3</td><td>\(50\,\text{m}\)</td><td></td><td></td><td>\(1500\,\text{m}^2\)</td></tr>
<tr><td>4</td><td>\(200\,\text{m}\)</td><td></td><td>\(1\,\text{km}\)</td><td></td></tr>
</table>
Hints
- For a missing side from an area, think of the side as a missing factor.
- Half the perimeter equals one length plus one width.
- Convert kilometers to meters before using the perimeter.
Solution
1. Rectangle 1: Since \(8 \times 12=96\), \(w=8\,\text{cm}\). Then \(P=2 \times (12+8)=40\,\text{cm}\).
2. Rectangle 2: Half of \(140\,\text{m}\) is \(70\,\text{m}\), so \(w=70-25=45\,\text{m}\). The area is \(25 \times 45=1125\,\text{m}^2\).
3. Rectangle 3: Since \(30 \times 50=1500\), \(w=30\,\text{m}\). Then \(P=2 \times (50+30)=160\,\text{m}\).
4. Rectangle 4: \(1\,\text{km}=1000\,\text{m}\), so half the perimeter is \(500\,\text{m}\). Thus \(w=500-200=300\,\text{m}\). For the area, \(200 \times 3=600\), then multiplying by \(100\) gives \(200 \times 300=60{,}000\,\text{m}^2\).
Answer
<table>
<tr><th>Rectangle</th><th>Length \(l\)</th><th>Width \(w\)</th><th>Perimeter \(P\)</th><th>Area \(A\)</th></tr>
<tr><td>1</td><td>\(12\,\text{cm}\)</td><td>\(8\,\text{cm}\)</td><td>\(40\,\text{cm}\)</td><td>\(96\,\text{cm}^2\)</td></tr>
<tr><td>2</td><td>\(25\,\text{m}\)</td><td>\(45\,\text{m}\)</td><td>\(140\,\text{m}\)</td><td>\(1125\,\text{m}^2\)</td></tr>
<tr><td>3</td><td>\(50\,\text{m}\)</td><td>\(30\,\text{m}\)</td><td>\(160\,\text{m}\)</td><td>\(1500\,\text{m}^2\)</td></tr>
<tr><td>4</td><td>\(200\,\text{m}\)</td><td>\(300\,\text{m}\)</td><td>\(1\,\text{km}\)</td><td>\(60{,}000\,\text{m}^2\)</td></tr>
</table>