mingja

Thanks, but I still do not get it:

How do you get

(root3)*r^2-1/2pai*r^2

May be I misunderstand the question.

Is it asking about the bigger 3-leaf-clover-shaped area formed in part by overlappings of 2 circles plus the center 3-cuured-sided smaller curved area?

Or is it asking about the middle 3-curved-sided smaller area?

Or something else?

I appreciate your reply! Thanks!

mingja

我也认为是B和C

75=3*5^2
98=2*7^2
140=2^2*5*7

Common multiple 公倍数m at least =2^2*3*5^2*7^2=14700

故 14700 can be divided by 49 , and also >14000

mingja

Agree

mingja

我同意思路该是两个概率的和

不过cannot understand BE SECRETARY的概率应该是9/10*1/9.

may be 9/10*1/9* (probablility that he is not treasurer)

=9/10*1/9*(7/8) ?

VICTOR_JZG

******2003-1-04******
今日无JJ，见谅！




To:joywzy,
20.
机井：36个数，分四组，每组从1到9，取出一个数，问取出的是几？
a. 取出后各个数和的unit digit是6
b. 取出后所有数的和是176
选d
[确认]D
思路:36个数，分四组，每组从1到9,则四组数总数为180,
a. 取出后各个数和的unit digit是6,由于每组数都小于10,那么180减去什么数后个位才能为6? 当然是4了;
b. 取出后所有数的和是176,那么180减去什么数后是176呢?当然是4了;
所以选D.

[此贴子已经被VICTOR_JZG于2003-1-5 12:44:33编辑过]

lisaislisa

to mingja
the shadow is the the triangel minus three'pei', each of which is 1/6 of the round

^^

VICTOR_JZG

原题:
三个等圆相切，中间夹空部分为阴影部分，其面积为64倍根号3-32派，求半径。不难，仔细算，ans: r=8
[确认] r=8
[思路]设半径为r，阴影部分面积=三角形面积-3*1/6圆的面积，即64倍(根号3)+32PAI=(根号3)*(r^2)-1/2PAI(r^2)，解得r=8。
步骤分别如下:
1. 因为是三个等圆相切,则各圆心连线构成等边三角形,设半径为r,则等边三角形边长为2r,高为root(2r)^2-r^2(勾股定理),可以求出等边三角形面积为(根号3)*(r^2);
2. 由于等边三角形的各个角为60度,那么每个扇形的面积应该为(PAI*r^2)/6,三个扇形的总面积就为1/2*PAI(r^2);
3. 根据题意可得(根号3)*(r^2)-1/2*PAI(r^2)=64倍(根号3)+32PAI,解方程可得 r=8.

应该比较清楚了吧!

lisaislisa

to victor :
34. x^2+6x+q, what is the value of q? D
1). X^2+6x+q=x^2+rx+r-2. some r is satisfied for this quotation. All variable X is satisfied for this
2). x^2+6x+Q= (x+m)(x+n), some m and n is satisfied for this quotation. All variable X is satisfied for this
[讨论]D
-------------------------------------------
my ans A

xing KU Le !

^^

VICTOR_JZG

To lisaislisa,
Thank you for your comments.

joywzy

thank u very much!