Vector help? Watch

saberahmed786
Badges: 13
Rep:
?
#1
Report Thread starter 4 years ago
#1
I'm stuck on this vector question and my method doesnt work :/

(iii) If the point S has position vector OS (3i -8j -7k) use a vector method to show that the points P, Q and S all lie on the same straight line.
OP (1i 2j 3k)
OQ (2i -3j -2k)
I thought if it lies on the same straight line then there would be a scalar k that would make it so multiplying any of the vectors by k I would get the other ones :/
0
reply
atsruser
Badges: 11
Rep:
?
#2
Report 4 years ago
#2
(Original post by saberahmed786)
I'm stuck on this vector question and my method doesnt work :/



I thought if it lies on the same straight line then there would be a scalar k that would make it so multiplying any of the vectors by k I would get the other ones :/
You need to find the vectors \vec{PQ},\vec{QS},\vec{SP} and check using your approach. These are the vectors that lie along the line (if that's the case). You have been given position vectors of the points i.e. the vectors that translate the origin to those points.

This will make more sense if you draw a diagram - you should always try to draw a diagram when doing vector problems (or any other problem, in fact).
0
reply
saberahmed786
Badges: 13
Rep:
?
#3
Report Thread starter 4 years ago
#3
(Original post by atsruser)
You need to find the vectors \vec{PQ},\vec{QS},\vec{SP} and check using your approach. These are the vectors that lie along the line (if that's the case). You have been given position vectors of the points i.e. the vectors that translate the origin to those points.

This will make more sense if you draw a diagram - you should always try to draw a diagram when doing vector problems (or any other problem, in fact).
I get
pq = (i -5j -5k)
qs = (i -11j -9k)
sp = (-2i 10j 10k)

I can see that pq and sp are the same because it's multiplied by -2 but what about qs?
0
reply
davros
  • Study Helper
Badges: 16
Rep:
?
#4
Report 4 years ago
#4
(Original post by saberahmed786)
I get
pq = (i -5j -5k)
qs = (i -11j -9k)
sp = (-2i 10j 10k)

I can see that pq and sp are the same because it's multiplied by -2 but what about qs?
You need to check your working for qs - I don't think that's right at all
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of East Anglia
    All Departments Open 13:00-17:00. Find out more about our diverse range of subject areas and career progression in the Arts & Humanities, Social Sciences, Medicine & Health Sciences, and the Sciences. Postgraduate
    Wed, 30 Jan '19
  • Aston University
    Postgraduate Open Day Postgraduate
    Wed, 30 Jan '19
  • Solent University
    Careers in maritime Undergraduate
    Sat, 2 Feb '19

Brexit: Given the chance now, would you vote leave or remain?

Remain (1129)
79.01%
Leave (300)
20.99%

Watched Threads

View All
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise