f1 to f2 mathemetics
2007-08-27 2:07 am
Peter has a wire which is 40 cm long. He wants to bend it into a shape such that it encloses a maximum area. Would you help Peter to find the ideal shape he wants?
回答 (2)
2007-08-27 2:29 am
✔ 最佳答案
shape:square (area:10*10=100)
2007-08-27 2:39 am
If Peter bend it into a circle, it enclosed a larger area than a rectangle:
Let r cm be the radius of the circle
Circumference of the circle = 2*pi*r = 2 *22/7*r = 40
r=6.36cm
Area of the circle = pi * r^2 = 22/7 * (6.36)^2 = 127.22cm^2
2007-08-26 18:40:20 補充：
Sorry, I mistyped rectangle in first sentence, it should be square.
Let r cm be the radius of the circle
Circumference of the circle = 2*pi*r = 2 *22/7*r = 40
r=6.36cm
Area of the circle = pi * r^2 = 22/7 * (6.36)^2 = 127.22cm^2
2007-08-26 18:40:20 補充：
Sorry, I mistyped rectangle in first sentence, it should be square.
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