Turn on thread page Beta
    • Thread Starter
    Offline

    9
    ReputationRep:
    the points A, B and C have position vectors, 2i + j + k, 5I + 7j + 4k, and i - j respectively.

    Prove A,B and C lie on a straight line
    Offline

    15
    ReputationRep:
    (Original post by sequence123)
    the points A, B and C have position vectors, 2i + j + k, 5i + 7j + 4k, and i - j respectively.

    Prove A,B and C lie on a straight line
    AB = (3,6,3)
    BC = (-4,-8,-4)

    These are multiples of one another and so AB and BC are in the same direction and ABC lie on a line
    • Thread Starter
    Offline

    9
    ReputationRep:
    AH i see, are there any other methods for showing thay all lie on the same line?
    Offline

    15
    ReputationRep:
    (Original post by sequence123)
    AH i see, are there any other methods for showing thay all lie on the same line?
    yes but I guess that's the quickest one.

    You could try writing down the general cartesian form of an equation in 3D and show that the three points make consistent constraints on the coefficicents but that'd be rather laborious
 
 
 
Turn on thread page Beta
Updated: May 14, 2005

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
  • Solent University
    Careers in maritime Undergraduate
    Sat, 2 Feb '19
  • Sheffield Hallam University
    City and Collegiate Campus Undergraduate
    Sun, 3 Feb '19
Poll
Brexit: Given the chance now, would you vote leave or remain?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Equations

Best calculators for A level Maths

Tips on which model to get

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.