數學知識交流 － 面積問題 (2)

(1) Let the bottom line be ABC, as it can be moved up and down which will not affect the length of 13cm, so the given information is not enough to do the calculation.
Ans : no answer .

(2) Let the triangle be CAB, where C is on the top, A on the left side, B at the bottom of right side.
The rectangle be DEBF, where DE is on the top, FB on the bottom.
Let M, N, P be the mid-pt of AC, BC and AB respectively. O be the centroid of triangle ABC.
Let (1) = |, (2) = ||, (3) = |||, (4) = ||||, (5) = |||||
Given that (4) = 10, (actually, (4) must be 10, as OB = 2*OM = 2*5 = 10)
As (4) + (5) = 16, so (5) = 6,
Also, OA = 2*ON = 2*(5) = 12, therefore (3) = 12
As DE = 10 + (3) = 10 + 12 = 22 = FB, and AB = 2*(3) = 24.
In triangle AFB, AF = 6, FB = 22, AB = 24, angle F = 90.
But 6^2 + 22^2 =/= 24^2
So the information is wrong.If I expect that AN =/= (3), then the blue area is :
rectangle DEBF - triangle ADC - triangle CEB - triangle AFB
= (10 + 12)*16 - 0.5(10 * 10) - 0.5(12 * 16) - 0.5(6 * 22)
= 140 cm^2.

please tell us the way

2012-03-29 18:52:05 補充：
I don't realy know what you mean ...

2012-03-29 21:06:30 補充：
MO ≠ BO !!!

2012-03-29 21:08:30 補充：
http://zh.wikipedia.org/zh-hk/%E5%87%A0%E4%BD%95%E4%B8%AD%E5%BF%83

2012-03-29 21:22:41 補充：
OH ... NOW I UNDERSTAND , THANKS

In Q2, it's actually no need to tell 5 cm...

2012-03-29 18:39:04 補充：
5=||||/2=10/2 since the centroid divides the medians into 2:1

2012-03-29 18:39:47 補充：
isnt it? im not quite gd at these.. -.-

2012-03-29 20:43:58 補充：
Please read see:

http://i1099.photobucket.com/albums/g395/jasoncube/1656744136-1.jpg

2012-03-29 21:21:06 補充：
i didnt say MO=BO!!!

i said MO=BO/2!!!!!!!

2012-03-29 21:29:28 補充：
Finally...

2012-03-31 11:04:31 補充：
It seems that there are many unnecessary information in Q2!~

2012-03-31 19:12:11 補充：
It seems that the information given in Q1 is not enough...