IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IGCSE/ GCSE => Math => Topic started by: holtadit on November 08, 2009, 12:26:28 pm

Title: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 12:26:28 pm
Find the attached question paper and diagram.

Here is the questions if you cant see the picture:

CY is paralled to OD
-->        -->
CX = 1/5 CD
-->
OC = c
-->
OD = d  and
-->
CY = nd
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 12:36:44 pm
Come on ya'll. HELP ME !!!  :'(
Title: Re: Vectors question - astar help me !!!!
Post by: nid404 on November 08, 2009, 12:58:36 pm
hmmm.....ill try
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 01:02:45 pm
a)
OC + CD = OD
=> CD = d-c
b)
  CX=1/5 CD
=>CX=1/5(d-c)
c)
OC + CX = OX
=> OX=c + 1/5d - 1/5 c
=>OX=4/5c + 1/5d
d)
CD  + DY = CY
=>DY = nd - d-c

i'll post e part in a few mins
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 01:05:21 pm
all right!!
i guess adi has answered them!!

very easy!
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 01:06:39 pm
Quote
all right!!
i guess adi has answered them!!

very easy!

No still has to do (e) which is the real MOFO !! i.e. im stuck on (e)
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 01:08:10 pm
wat is e question???
is it find the value of d or a!!
didnt get it!!
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 01:09:30 pm
e)
OX=1/5d + 4/5c
DY=nd-d-c = n-1(d) - c
Because they are parallel,
we take the ratio of their components...
(1/5)/(n-1) = (4/5)/1
=> 4n/5 -4/5 = 1/5
=>4n/5 = 1
=>n= 5/4
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 01:11:43 pm
great dude!!
good solution!!
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 01:12:34 pm
No still has to do (e) which is the real MOFO !! i.e. im stuck on (e)
tell me if u still dont get it ari!!
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 01:14:58 pm
actually when i read it and tried to understand i did not understand why are you taking ratio???

and ari this question from which year!??
is it add. math!!
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 01:15:52 pm
now u understand it shrey???
its cuz u have to get the scale factor naa.....
nd i dont think this is add. maths...quiet simple..
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 01:22:33 pm
Ill look at the answer in a bit (im doing eco papers right now). This is from my textbook By the way.

+rep to aditoxic
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 01:23:43 pm
now u understand it shrey???
its cuz u have to get the scale factor naa.....
nd i dont think this is add. maths...quiet simple..
i also thought abt it for some time!!
but then math paper is also over!!
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 01:28:59 pm
Shreycool im doing my IGs in 2010.

Im simply preparing for them NOW.
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 01:30:13 pm
Shreycool im doing my IGs in 2010.

Im simply preparing for them NOW.
ohh great!!
m/j or oct/nov??
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 01:36:24 pm
ur welcome ari..nd ya do let me know if i was right or wronng....
nd Thanks for the rep
Title: Re: Vectors question - astar help me !!!!
Post by: nid404 on November 08, 2009, 01:39:38 pm
Thanks for answerin it.....m on ma phone nw....couldn't help
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 01:41:38 pm
kkk!!

take ur time!!
tell us if you getting the same ans!!
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 02:06:17 pm
yur answer for (e) is correct aditoxic.

Thanks once again !!!

I answer my IGs in may 2010
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 02:08:33 pm
ohh dts gr8...i thot it shud be correct...
ur welcome ari...
keep posting questions like this nd let me answer all of them nd u give me reps...hahaha...lol...jking :D
Title: Re: Vectors question - astar help me !!!!
Post by: nid404 on November 08, 2009, 02:11:09 pm
yaa that correct...i jst solved it
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 02:11:46 pm
good job both of you!!
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 02:30:45 pm
Quote
ohh dts gr8...i thot it shud be correct...
ur welcome ari...
keep posting questions like this nd let me answer all of them nd u give me reps...hahaha...lol...jking Cheesy

Ill take you up on your proposition: HERES ANOTHER ONE

AC is parallel to OB
-->         -->
AX = 1/4  AB
-->
OA = a
-->
OB = b   and
-->
AC  = m


(a) Express AB in terms of a and b
(b) Express AX in terms of a and b
(c) Express BC in terms of a,b, and m
(d) Given that OX is parallel to BC find the value of m ----------> stuck on this
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 02:37:23 pm
AC is parallel to OB
-->         -->
AX = 1/4  AB
-->
OA = a
-->
OB = b   and
-->
AC  = m


(a) Express AB in terms of a and b
(b) Express AX in terms of a and b
(c) Express BC in terms of a,b, and m
(d) Given that OX is parallel to BC find the value of m ----------> stuck on this
a)
OA+AB=OB
AB=b-a
b)
Ax= 1/4(b-a)
c)AB+BC=AC
BC=mb - b + a
d)OX=OA+AX
OX=a + 1/4b - 1/4a
OX= 1/4b + 3/4 a
BC=mb - b + a = m-1(b) + a

therefore, doing the same thing as b4, finding theratio

(1/4)/(m-1)=(3/4)/1
3m/4 - 3/4 = 1/4
3m/4 = 1/4 + 3/4
3m/4 = 1
3m = 4
m=4/3
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 02:38:43 pm
arre!
you now becoming faster dude!!
i cudnt eve see this question!!
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 02:39:43 pm
haha...this is what happens when m vella...which is quiet rare...
bt when i am vella...i can be as quick as u can think
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 02:40:32 pm
vela??
u talking abt player or something else??
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 02:41:33 pm
vella as in free!!!
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 08, 2009, 02:42:14 pm
ohhkk..!!
actualy i was answering in physics help ka thread!!
wassup had a doubt!
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 02:42:30 pm
aditoxic my answer book says that m = 4/3  :-\

What's wrong ?
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 02:42:53 pm
gimme 2 mins!!
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 03:03:53 pm
Quote
gimme 2 mins!!

any luck man ???
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 03:06:12 pm
yeah done ari..i've made the changes nd bolded my mistake so u know...just took 1/4 instead of 3/4 in a hurry
Title: Re: Vectors question - astar help me !!!!
Post by: holtadit on November 08, 2009, 03:14:14 pm
Quote
therefore, doing the same thing as b4, finding theratio

(1/4)/(m-1)=(3/4)/1
m/4 = 1/4 + 3/4
m=4/3

I dont get what u have done here.

How did u get 0.25/(m-1)=0.75/1 ???

What were the steps ?

   
Quote
m/4 = 1/4 + 3/4
m=4/3     
how did u get m/4 and how, following your calculations, did u get 4/3 when 0.25 + 0.75 = 1 * 4 =4
Title: Re: Vectors question - astar help me !!!!
Post by: @d!_†oX!© on November 08, 2009, 03:19:12 pm
i am sooo sorry ari dt i cud not explain u in a gud way...too busy preparing for my own paper for tom..anyways i have editted it again for more clarity...temme if u still need more assistance...i dont think u will now
Title: Re: Vectors question - astar help me !!!!
Post by: ~~~~shreyapril~~~~ on November 09, 2009, 05:59:01 am
hey one suggestion did ya do the changes in bold!!