About 08 HKCEE AMaths

👨🏻‍🏫 學術台數學

尋找理想伴侶中

2008-05-22 12:15 am

If I do like this : am I wrong? If wrong, plz tell me the mistake.
圖片參考：http://hk.geocities.com/doortyui/amath1.jpg

Next questions, It is find the tangent's equation?
that means dy/dx? If wrong, plz give the suggected answer for me

圖片參考：http://hk.geocities.com/doortyui/amath2.jpg

the more difficult question///
how to do this questions?

圖片參考：http://hk.geocities.com/doortyui/amath3.jpg

更新1:

such that PB = 2AP, find the uint vector in the direction of OP

回答 (1)

用戶10012

2008-05-22 12:52 am

✔ 最佳答案

Question 2 and question 6 are correct.
For Q.7
AB=OB-OA=5i + 6j -2i -3j=3i +3j.
OP=OA + AP where AP=mAB and m=1/(1 + 2)=1/3 because PB=2AP.
Therefore OP=(2i + 3j) + 1/3(3i + 3j)= 2i + 3j + i + j = 3i + 4j.
Therefore, unit vector of OP= (3i + 4j)/sqrt (3^2 + 4^2) = 1/5(3i + 4j).

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