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

Qualification => Subject Doubts => IGCSE/ GCSE => Math => Topic started by: ~~~~shreyapril~~~~ on October 20, 2009, 03:11:59 pm

Title: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 20, 2009, 03:11:59 pm
i have this question please answer it Astar math or slvri i need help
Please help wid diagram if possible..


Points A and B have position vectors a and b respectively relative to the origin O. The point C lies on OA produced such that OC = 2OA, and d lies on OB such that OD = 1/3OB

i) Express BC and DA in terms of a and b
   The lines AD and BC intersect at P when extended
ii) Given that AP = mDA, express OP in terms of m, a, b
iii) Given also that BP = kBC, express OP in terms of k, a, b
iv) Hence calculate the value of m and k and the position vector of p
v) Another point Q is such that APCQ is a parallelogram. Find its position vector.

Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: astarmathsandphysics on October 20, 2009, 03:36:32 pm
here
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 20, 2009, 03:47:22 pm
tks sir
i did not get the step in the attachment
how come QC = AP
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 20, 2009, 03:48:38 pm
i guess 2a - (3a - b) = b-a
rite?? or not??
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: astarmathsandphysics on October 20, 2009, 03:49:03 pm
Because QCAP is a paralellogram. It goes APQC so AP is antiparalle to QC so paralell to CQ. I should have crawn it on. Sorry.
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: astarmathsandphysics on October 20, 2009, 03:49:47 pm
i guess 2a - (3a - b) = b-a
rite?? or not??

yes my mistake
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 20, 2009, 03:50:51 pm
k thanx sir got it...
i will come back if i have some more doubts

Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: Ghost Of Highbury on October 20, 2009, 04:20:46 pm
refer to the diagram..

1) BC = 2a - b
    DA = -b/3 + a
2) OP = OA + AP
    OP = a(1+m) -mb/3
3)   OP = OB + BP
      OP = b + 2ak - bk
4)    2k = 1 + m
       1 - k = -m/3
solve them
m =3
k=2
---------
first find QC = AP = 3a - b

therefore, CQ = b-3a

OQ = OC + CQ

= 2a + b - 3a = b-a
-----
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 21, 2009, 11:33:10 am
go it mannn
thanx.
by the way what name did you give to the image??
dhan tana!!!
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: astarmathsandphysics on October 21, 2009, 12:08:28 pm
AM I will have to learn to do images as good as that.
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: Ghost Of Highbury on October 21, 2009, 12:09:27 pm
Quote from: astarmathsandphysics on October 21, 2009, 12:08:28 pm
AM I will have to learn to do images as good as that.

sir, its nuthing complicated..use MS paint..
thats it!
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 23, 2009, 11:43:28 am
i thought you used photoshop cause i heard u pretty well in it
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: astarmathsandphysics on October 23, 2009, 12:21:58 pm
At themoment i only use openoffice. I dont have much ms software.
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 23, 2009, 05:26:49 pm
ohh
y dont u use a torrent and download it
By the way i guess paint is by default in every pc i guess
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: astarmathsandphysics on October 23, 2009, 05:32:59 pm
I will get ms office
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 23, 2009, 05:35:01 pm
u not having ms office so wat u use mac or something else cause i think u cant work without ms office
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: Ghost Of Highbury on October 23, 2009, 05:37:12 pm
Quote from: ~~~~shreycool~~~~ on October 23, 2009, 05:35:01 pm
u not having ms office so wat u use mac or something else cause i think u cant work without ms office

sir uses open office. thats what he said
Title: Re: Add. Maths!!!!! please help slvri/Astar math
Post by: ~~~~shreyapril~~~~ on October 23, 2009, 05:44:20 pm
arre hahahaha
frgt
really  :-[ :-[ :-[