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Relate area and perimeter

Area measures the number of square units covering a region, while perimeter measures the linear units around its boundary; these are different attributes with different units. For rectangles with whole-number side lengths, the dimensions determine both quantities, and figures can have the same perimeter but different areas or the same area but different perimeters. This understanding is limited to familiar rectangular figures and does not include optimization or general formulas for arbitrary polygons.

Detailed Explanation: Relate area and perimeter

Area and perimeter describe different parts of a rectangle:

  • Area tells how much space is inside. It is measured in square units.
  • Perimeter tells the distance around the outside. It is measured in linear units, such as feet or meters.

Example

A rectangular rug is 66 feet long and 33 feet wide. Find its area and perimeter.

Step 1: Find the area.

Area counts the square units covering the rug:

6×3=186 \times 3 = 18

The area is 18 square feet\boxed{18\text{ square feet}}.

Step 2: Find the perimeter.

Add the lengths of all four sides:

6+3+6+3=186+3+6+3=18

The perimeter is 18 feet\boxed{18\text{ feet}}.

Notice that both answers have the number 1818, but they do not mean the same thing. The area is 1818 square feet inside the rug, while the perimeter is 1818 feet around its edge. The units help show which measurement you found.

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Perimeter of a Rectangle - Perimeter from Area and Side


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