My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum

LinkBack Thread Tools Display Modes
September 24th, 2012, 10:37 PM   #1
Joined: Mar 2009

Posts: 2
Thanks: 0

Homogeneous Eqn of Line given 2 homogeneous points

I'm reviewing Projective Geometry. This is an exercise in 2D homogeneous points and lines.

Given two points p1 (X1,Y1,W1) and p2 (X2,Y2,W2), find u = (a, b, c) of the line (aX + bY + cW = 0). (See, "Similarly, given two points p1 and p2, the equation..." and ... ode16.html, "Recall from the Section 2 that the coordinates...".)

The solution by means of linear algebra is u = p1 x p2 (cross product) = (Y1W2-Y2W1, W1X2-X1W2, X1Y2-Y1X2). I have worked out how to obtain that by calculating a determinant. However, I should be able to get the same result by using elementary algebra, but somewhere I take a wrong turn. Can someone provide at least the starting point?
LouArnold is offline  

  My Math Forum > High School Math Forum > Algebra

eqn, homogeneous, line, points

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Non- homogeneous r-soy Calculus 4 February 17th, 2013 05:54 PM
homogeneous r-soy Calculus 7 February 17th, 2013 01:36 PM
Homogeneous equation fantexihong Calculus 4 September 20th, 2012 10:55 AM
Help: Homogeneous functions. azer Real Analysis 1 December 31st, 2011 04:07 AM
Homogeneous systems remeday86 Linear Algebra 1 June 27th, 2010 11:58 AM

Copyright © 2019 My Math Forum. All rights reserved.