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標題: maths question(p.6) pls reply now [打印本頁]

作者: 高達(0079) 時間: 12-4-19 21:48 標題: maths question(p.6) pls reply now

The diameter of a circle is the same as the side of a square. If a string is tied around the circle or the square, which one needs a longer string to tie around it? Why?

作者: cowmoon 時間: 12-4-19 22:25

length string required to tie around the shape = perimeter of the shape

perimeter of a square = 4 x side
perimeter of a circle = pi x diameter = 3.141592654 x diameter

so which one is longer ?

作者: Derdad 時間: 12-4-27 02:19

高達(0079) 發表於 12-4-19 21:48
The diameter of a circle is the same as the side of a square. If a string is tied around the circle ...

Let D be the side of the square. D is also the diameter of the circle.

Perimeter of the square = 4D
Circumference of the circle = 3.14D

梗係4D大過3.14D啦！

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