请教Prep 数学两题

pighappy · 发表于 2010-5-14 11:42:53

The figure shows the top side of a circular medallion made of a circular piece of colored glass surrounded by a metal frame, represented by the shaded region. If the radius of the medallion is r centimeters and the width of the metal frame is s centimeters, then in terms of s and r, what is the area of the metal frame, in square centimeters?

图是一个圆圈中间镂空外框shaded... 答案是 pi*s(2r-s)...

还有一题
If @ denotes one of two arithmetic operations, addition or multiplication, and if k is an integer, what is the value of 3 @ k ?

(1) 2 @ k = 3

(2) 1 @ 0 = k

DS的答案是 1 alone is sufficient...这是为什么那~ 1能推出两个答案啊~

请教。。。谢谢。。。

gracezz · 发表于 2010-5-14 12:00:23

阴影是不是应该等于 [r2-（r-s)^2]pi 一减就是你那个答案。这题主要得理解到那个R是大圆的半径。

第二个在条件1下，2只能加K=3，K=1，因为如果2*K，K又是整数，应该得一个偶数而不是三，所以K=1那个法则是加油，所以等于四了

楼主用的prep啥版本的？我的prep破解里面好多题不全。要么没图要么答案不全。。。。楼主的全吗？

请教Prep 数学两题

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