Greenwood press
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book-20600
CIRCLES
13 A trundle wheel can be used to measure long distances by mul- tiplying the number of its revo- lutions by its circumference. The age of a tree is related to the number of its rings and its circumference. with a diameter of 16 inches for $16. Is that a reasonable deal? Since the amount of pizza is related to its area, it would be more beneficial if the consumer were told the unit cost of the pizza per square inch. Instead, consumers may develop a misconception and think that the 16-inch pizza should be 16/12, or 4/3, as much as the 12-inch pizza. In the 12-inch pizza, the radius is 6 inches. So the area of the pizza is π(6) 2 ≈ 113.1 square inches. At a sale price of $10, the consumer is paying about 8.8 cents per square inch of pizza. In the 16-inch pizza, the radius is 8 inches. So the area of the pizza is π(8) 2 ≈ 201.1 square inches. At a sale price of $16, the consumer is paying about 8.0 cents per square inch of pizza. At first glance, one might think the 12-inch pizza is a better buy, but actually it is the other way around. Since volume purchases usually have a cheaper unit price, these prices seem pretty reasonable. Is this true about the prices at your favorite pizza shop? The area of a circle is helpful to farmers in determining the amount of space that a sprinkling system will cover. As a sprinkler rotates, it will spray water in a circular pattern, or in a sector of a circle if it is restricted in a certain way. The distance the water reaches, or the radius of the circle, is sufficient information for the farmer to determine how much space will be covered by the water and how many sprinklers are needed to water the crops. Crops are often created in rectan- gular grids to make harvesting easier, but watering in a rectangular pattern is often less efficient than in a circular pattern. Therefore, the challenge in watering crops is to determine how many circles can be packed into the rectangle region. The trick for the farmer is to automate the sprinklers so that they provide just the right amount of water to the crops to optimize production and minimize expense. A circle is a figure that has an optimal area based on its perimeter. Based on a given perimeter, there is not another shape that has an area greater than a cir- cle. Similarly, based on a given area, there is not another shape that has a smaller perimeter than a circle. In essence, this information indicates that a great way to make use of materials and space is to form circles. Think about all the objects made of raw materials that are shaped into circles, such as plates, cups, pots, compact discs, and digital video discs. All of these objects are designed to hold substances or information that take up space in a resourceful way. Parts of circles Download 1.81 Mb. Do'stlaringiz bilan baham: |
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