Form 3 maths (mc)

D係答案

B對係因為:當J以90度轉到去K嘅時候,K嘅座標就會係J嘅座標調番轉。你可以試下,係真+!!例如:如果J嘅座標係(3,5)嘅話,咁K嘅座標就會係(-5,3),x軸係負數由於K位於負x軸嘅上面。而佢話K係(-y,x),其實入面嘅y同x只係一個代數,5係分別代表著y軸同x軸。如果要表示x軸同y軸,係括號入面嘅先後次序已經代表左啦!!如果5明嘅話,咁就睇番我上面嘅例子啦!!

A對係因為:由B對得知K嘅座標係(-y,x),用計距離嘅公式。就可以知道OJ=OR

C對係因為:當J垂直於x軸上而相交於M點時,兩者嘅x軸座標會係一樣。而M嘅y軸就會係0,所以M座標=(x,0)

D錯係因為:冇證據可以證明到角KON=角JOM,所以5能透過角KON+角JOM=90度而去搵角JOM=45度

B瓜,我都唔係好清楚

我知道真正答案a~
答案係D
佢要你搵唔ARM的答案
而唔係ARM個D~
A , B , C 都係ARM的
不過正確答案係D
我保證一定ARM

The answer is B.
Because the correct coordinates of K is (-x,y)

∆OJM is equal to ∆OKN (RHS)
So, OJ = OK

and ∠JOM = ∠KON = a
So, a + a + 90度 = 180度
So, a = 45度
So, ∠JOM = 45度
Therefore, A and D is correct and they are not answer.

For answer C, the coordinates of M is (x,0)
Thus, answer C is correct and it is not an answer.

answer係B
應該係(-x,y),而唔係(-y,x)

b囉,,因為x要係頭(x,?)
唔係(?,x)

b, because it should be like (x-axis, y-axis), but they turn it around in the other way..

so that why b was wrong..!!

B
I am only try and i am only a s1.

2007-11-09 17:58:53 補充：
you can see that a is correct by you eyesd is easy to know that it is correct tooAnd there are B and C left so i think B is incorrect.

2007-11-09 17:59:55 補充：
應該係(-x,y),而唔係(-y,x)

我覺得b係答案
因為條題目係問邊個係incorrect
咁姐係有3個statement係岩啦
a係岩既因為你用眼睇都睇到啦
b係錯係因為coordinates係寫x axis跟住先寫y axis
同埋x axis個度應該係negative而唔係positive
而y axis個度應該係positive而唔係negative
c係岩既因為佢係寫x axis先,跟住先寫y axis
d係岩既因為x axis同y axis個到form左個right angle
所以angle JOM 係45度係岩既
答案a,c,d都係correct answer
咁b就係incorrect answer

(a) is correct
it is because those triangle is a congrue triangle

2007-11-09 17:52:40 補充：
answer (b) must wrongas the coordiante的次序 is wrong already.

answer is B

2007-11-09 17:51:10 補充：
use yr brain and think and you can understand

2007-11-10 09:57:00 補充：
many of you now can think, I am glad you know that the required ans. is the "incorrect one", not the "correct ones", most of them can get the reason why the ans. should be "B", you guys are excellent. haha :)