[計量] 請教幾題計量問題!
1. Rectangle ABCD has AB=4 and BC=3.
__ __
Segment EF is constructed through B so that EF ┴ DF,
__ __ __
and A and C lie on DE and DF, respectively. What's EF?
Ans：125/12
這題題目是看的懂，可是圖一直畫不出來，卡在條件EF直線垂直DF直線
請問有高手可以解釋一下圖怎麼畫，還有答案怎麼求嗎? 謝謝~
2. Two cubical dice each have removable numbers 1 through 6.
The twelve numbers on the two dice are removed, put into a bag,
then drawn one at a time and randomly reattached to the faces of the cubes,
one number to each face.
The dice are then rolled and the numbers on the two top faces are added.
What is the probability that the sum is 7?
Ans：2/11
這題的機率排列組合就真的有點搞不懂怎麼算了，
其中把12個數字丟到袋子裡再一一抽出來放到骰子上，
所以變成一個骰子上的數子有可能是重複的，
這個部份的排列組合一直想不出要怎麼算吶
還是要請教高手一下!
3. Let a,b,c and d be real numbers with |a-b|=2, |b-c|=3, and |c-d|=4.
Indicate『all』possible values of a-d.
(a)-9
(b)-5
(c)-3
(d)-2
(e) 1
(f) 3
(g) 9
Ans：(a,b,c,e,f,g)
這三題遇到障礙算很久搞不清楚，第一提根本是連圖都畫不出來啊
麻煩大家了，感激不盡!!
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04/02 00:05, , 1F
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04/13 23:36,
7年前
, 12F
04/13 23:36, 12F
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