Perimeter and area - need explanation

In summary, the dimensions of a rectangle with sides a=2 and b=5 have a perimeter of 14 and an area of 10. If a rope with a length of 14m is used to encircle the rectangle and connect the ends, it will have the same perimeter. However, if the rope is used to make a circle, its perimeter will still be 14, but the area will be 15.597. This is because area and perimeter are not the same measurements. Land is measured in area because it gives a more accurate representation of the space being occupied, rather than just the boundary. There is no easy formula for measuring land with irregular boundaries, as it would require complex calculations and measurements.
  • #1
PeteCA
2
0
Dimensions of rectangle are a=2 and b=5.

Perimeter and area P=2a+2b=14 and A=a*b=10

If we take a rope of length l=14m, encircle the rectangle and connect the ends we will have the same perimeter.

Now we take this rope and make circle of it, this circle will have the same perimeter of rectangle P=14.

Radius is r=(14)/(2*pi)= 2.228

Area of circle will be A=r*r*pi=2.228*2.228*pi=15.597

Why area of circle A=15.597 is not the same as area of rectangle A=10 ?
 
Mathematics news on Phys.org
  • #2
Because area is not the same as perimeter. Take that circle of yours and crush it flat (well, almost; you can't really crush it into a line...); it now has ~zero area and the same perimeter. Incidentally, it's possible for a figure to have finite volume and an infinite perimeter.
 
  • #3
Then why is land mesured in area and not perimeter, every mesure will give different results.

Is there a formula or easy way to mesure land if boundaries are like potato.
 
Last edited:
  • #4
PeteCA said:
Then why is land mesured in area and not perimeter, every mesure will give different results.

Is there a formula or easy way to mesure land if boundaries are like potato.

Because no one cares what the perimeter is, and no one wants to end up buying property with zero square feet because some sales rep was clever in advertising the place.
 
  • #5


The reason why the area of the circle is not the same as the area of the rectangle is because they are two different shapes with different formulas for calculating their areas. The area of a rectangle is calculated by multiplying its length (a) by its width (b), while the area of a circle is calculated by multiplying the square of its radius (r) by pi. In this case, the rectangle has an area of 10 square meters, while the circle has an area of 15.597 square meters. This is because the circle has a larger radius (2.228 meters) compared to the width of the rectangle (2 meters). It is important to remember that even though the perimeter may be the same, the area will be different for different shapes.
 

What is the difference between perimeter and area?

Perimeter refers to the distance around the outside of a shape, while area refers to the amount of space that a shape covers.

How do you calculate the perimeter of a shape?

To calculate the perimeter of a shape, you need to add up the length of all its sides. For example, if a rectangle has sides of 5 cm and 10 cm, the perimeter would be 5 + 5 + 10 + 10 = 30 cm.

What is the formula for calculating area?

The formula for calculating area varies depending on the shape. For a rectangle, it is length x width. For a circle, it is π x radius^2. For a triangle, it is 1/2 x base x height. It is important to know the specific formula for each shape in order to accurately calculate area.

What units are used to measure perimeter and area?

Perimeter is typically measured in units of length, such as centimeters, meters, or feet. Area is measured in units squared, such as square centimeters, square meters, or square feet.

Why are perimeter and area important in math and science?

Perimeter and area are important concepts in math and science because they help us understand the size and shape of objects. They are also used in various real-world applications, such as building design, land surveying, and determining the amount of materials needed for construction projects.

Similar threads

Replies
21
Views
3K
Replies
2
Views
792
Replies
1
Views
1K
Replies
2
Views
1K
  • General Math
Replies
1
Views
7K
  • Precalculus Mathematics Homework Help
Replies
1
Views
2K
  • Precalculus Mathematics Homework Help
Replies
2
Views
1K
Replies
4
Views
1K
Replies
32
Views
902
Replies
4
Views
4K
Back
Top