Solving Vectors Problem: Proving Collinearity

  • Thread starter Thread starter Karate Chop
  • Start date Start date
  • Tags Tags
    Vectors
AI Thread Summary
The discussion revolves around a vector problem involving three concurrent lines OA, OB, and OC extended to points D, E, and F. The objective is to prove that the intersection points of lines AB and DE, BC and EF, and CA and FD are collinear. The original poster has attempted to equate the equations of the lines but encountered difficulties with simultaneous equations involving multiple variables. Another participant expresses confusion about the question, indicating a need for clarification. The thread highlights the challenges of solving vector problems and the importance of clear communication in mathematical discussions.
Karate Chop
Messages
18
Reaction score
0
Hi, I'm having a few troubles with this question on my assignment. I've tried for many hours to get out the answer but i keep getting stuck and am not sure if I'm going about it the right way.

This is the question:

Three concurrent lines OA, OB and OC are produced to D, E and F respectively. Prove, using vectors, that the point of intersection of AB and DE, BC and EF, CA and FD are collinear.

What worked out the equations of the lines going through the points A and B, D and E, etc. and then made the equations of lines through A and B and D and E equal each other, since they were the position vectors of any point along that line. I did this inorder to try to get the points D, E and F in terms of a, b and c (the position vectors of A, B and C respectively), however in my last and most successful attempt at this question, i end up with 3 sets of two simultaneous equations, each set had three different variables so i couldn't solve it. Please help! thanks in advance. john.
 
Physics news on Phys.org
Has anybody gone anywhere useful with it?
 
Karate Chop said:
Has anybody gone anywhere useful with it?

Attach a figure. I do not understand the question.

ehild
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top