Wednesday, February 10, 2010

As the perimeter of any rectangle increases so does its area. true or false?

if true say why it is true and if false show a reason why it is falseAs the perimeter of any rectangle increases so does its area. true or false?
false!! take a 3*2 rectangle its perimeter is 10 and it's area is 6. take a 4*1.5 rectangle it's perimeter increased to 11 but it's area is still 6!!As the perimeter of any rectangle increases so does its area. true or false?
As a suggested rule, it's false.





As a question, it's neither true nor false.





It can, or it can also not, depending on the details of the change. For example, say you have a rectangle that is 20 x 10, perimeter = 60, area = 200. Increase the perimeter by adding 30 to both long and short sides and you have a rectangle that is 50 x 40, perimeter = 180, area 2,000. Sure enough, you increased the perimeter and the area increased.





However, consider the same rectangle and lengthen the long side to 24, but shorten the short side to 8. Now you have a rectangle of 24 x 8, perimeter = 64, area = 192. You have increased the perimeter from 60 to 64, but the area fell from 200 to 192.





Since there is a case that meets the rule's operation but not its result, the rule is incorrect.








Added:





(I altered the first example to address what a later Answerer said. As you can see in that example, you CAN change both dimensions at once and have the proposed rule seem valid. The point is that it is the particular details of the change that determines if area increases as perimeter does, not whether both dimensions are changed at once rather than just one of them changing. Granted, if only one changes, it will seem to be valid, but that is a result of the details, not the salient feature. If you can change both at once you can make it not hold, but clearly you can also make a ';change both'; example that lets it seem to hold.)
true because of Length times width, if the numbers are getting bigger than the multiplication answer is getting bigger
If you can change both sides at the same time, it's false.





Consider a 5x4 rectangle vs a 10x1 rectangle

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