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【OG20-P173-177题】
In the figure shown, if the area of the shaded region is 3 times the area of the smaller circular region, then the circumference of the larger circle is how many times the circumference of the smaller circle?
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题目:如图所示,假设阴影部分的面积是小圆面积的3倍,问大圆周长是小圆周长的几倍?
解答:
1.假设大圆半径为R,小圆半径为r。
2. 大圆的面积=小圆面积+阴影面积,而已知阴影面积=3倍小圆面积,因此大圆面积=4倍小圆面积,也就是πR2=4πr2,由此可以得出R=2r。
3. 大圆的周长/小圆的周长=2πR/2πr=R/r=2.
题目讨论 (3条评论)

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贾思敏
好气哦这道题没看清楚是阴影面积是小圆面积的三部,我还以为是大圆的面积是小圆的3倍害
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0 回复 2021-08-22 22:31:27
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emily666
容易算成3倍,要注意
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0 回复 2020-04-03 11:31:20
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Elaine750
未知数要设清楚
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0 回复 2019-11-03 14:58:35