【纪念当年的帖子（2010）】Add Maths功课讨论区

dollyeye

then hoe to do ?

乙劍真人

then hoe to do ?
dollyeye 发表于 23-4-2010 06:42 PM

类似题目的回答 TIPs:

Step 1: 把资料画成图..

Step 2: 把 ratio 换成分数看：OC = 3CB
                                 OC/CB = 3/1
                               OC : CB = 3:1 ---(1)

since OB = 4q, then from (1) OC = 3q; CB = q

* since S, E & B is collinear --> SE = h SB

dollyeye

1.Given a triangle OAB with  —>OA=5a  and  —>OB=10b .D is the midpoint of OA and C is a point on AB such that ACB=4:1. M is a point on OC such that           —>OM=nOC . Find the value of n if B,M and D are collinear.

dollyeye

1.  Given a triangle OAB with  —>OA=5a  and  —>OB=10b .D is the midpoint of OA and C is a point on AB such that ACB=4:1. M is a point on OC such that
—>OM=nOC . Find the value of n if B,M and D are collinear .
2.  A,B,C and D are four points in a Cartesian plane with O as the origin.Given       —>OA=2i+7j , —>AB=-i+6j and —>OC=4/3AB.D is a point on AC such that AD=nAC.
(a) Find —>OB,—>OC and —>AC
(b)OD is parallel to DB, find the valu of n.

dollyeye

1.  Given a triangle OAB with  —>OA=5a  and  —>OB=10b .D is the midpoint of OA and C is a point on AB such that AC : CB=4:1. M is a point on OC such that
—>OM=nOC . Find the value of n if B,M and D are collinear .
2.  A,B,C and D are four points in a Cartesian plane with O as the origin.Given       —>OA=2i+7j , —>AB=-i+6j and —>OC=4/3AB.D is a point on AC such that AD=nAC.
(a) Find —>OB,—>OC and —>AC
(b)OD is parallel to DB, find the valu of n.

dollyeye

1.  Given a triangle OAB with  —>OA=5a  and  —>OB=10b .D is the midpoint of OA and C is a point on AB such that AC : CB=4:1. M is a point on OC such that—>OM=nOC . Find the value of n if B,M and D are collinear .
2.  A,B,C and D are four points in a Cartesian plane with O as the origin.Given       —>OA=2i+7j , —>AB=-i+6j and —>OC=4/3AB.D is a point on AC such that AD=nAC.
(a) Find —>OB,—>OC and —>AC
(b)OD is parallel to DB, find the value of n.

dollyeye

怎样做》》？？

永遠愛著許瑋倫

请教一题integration...谢谢
2
    (x+1)(3x-2)/(2x^4)  dx
-2
这里不能写那个符号...希望能看得懂

Enceladus

回复 442# 乙劍真人

我做高级数学时又遇到了问题，trigonometry的。。。

Given that sin a =k such that a is an acute angle, express cot a in terms of k.


说实在一句话，我完全不懂他问什么。。。

Enceladus

最近老师教完了trigonometric functions，做到有点晕。很难理解一下的，他的题目。。。

乙劍真人

回复  乙劍真人

我做高级数学时又遇到了问题，trigonometry的。。。

Given that sin a =k such that a is an acute angle, express cot a in terms of k.


说实在一句话，我完全不懂他问什么。。。

哦.. 这个 pattern 的题目啊.. 把它换成图再跟着 A O H 来做就可以了..

shin93

我不知道它要的到底是什么 = =
请教一下...

Enceladus

回复 442# 乙劍真人


   刚才你教我的，我看懂了。对不起，延迟答复因为网络出现问题。我这边有一题不会做，请帮帮我，谢谢。以下是我的题目。。。
   Given that sin x = cos x such that 90<x<270, find the value of cot 1/2 x.

   谢谢

Enceladus

卡帖了，卡帖了。

Enceladus

最近几天的网路好像怪怪的，超慢。。。。。

harry_lim

回复  乙劍真人


   刚才你教我的，我看懂了。对不起，延迟答复因为网络出现问题。我这边有一题不会做 ...

Given that sin x = cos x such that 90<x<270, find the value of cot 1/2 x.

Enceladus 发表于 27-4-2010 11:20 PM

sin x = cos x

sin x/cos x = 1

tan x = 1

x = tan^-1 (1)

x = 45度

90 < x < 270在quadrant 2和3

quadrant 2 :

x = 180 - 45 = -135度(在negative)

quadrant 3 :

x = 180 + 45 = 225度(在positive)

therefore, x = -135度 or 225度


=================
cot 1/2 x度我不會做

harry_lim

Katie
卡帖

Enceladus

回复 456# harry_lim


   我算到cos x 是-1，够力。真是错到离谱。

harry_lim

回复  harry_lim


   我算到cos x 是-1，够力。真是错到离谱。
Enceladus 发表于 28-4-2010 12:04 AM

我已經編輯了。。。你再看多一次

Enceladus

回复 456# harry_lim


   哈哈，谢谢你的好意。无论如何，我还是很感激你的帮忙。