Linear Algebra 1 problem, Vector Geometry: Lines

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Discussion Overview

The discussion revolves around a problem in linear algebra concerning vector geometry, specifically finding points on a given line that are a certain distance from a specified point. The problem involves determining all points on the line L: x = (-3, 1) + t(1,-2) that are 2 units away from the point (-3, 1).

Discussion Character

  • Exploratory, Technical explanation, Mathematical reasoning

Main Points Raised

  • One participant states the problem and mentions a potential solution but expresses uncertainty about how to begin.
  • Another participant suggests writing down the distance between points on the line and the specified point to facilitate solving the problem.
  • A different approach is proposed involving the intersection of the line with a circle centered at (-3, 1) with a radius of 2, indicating the need to set up the equation for the circle.
  • Another participant suggests stepping along the line to find a point that is exactly 2 units away from (-3, 1) by calculating the distance between the two points.

Areas of Agreement / Disagreement

Participants present multiple approaches to the problem, indicating that there is no consensus on a single method to solve it. Various strategies are suggested without agreement on which is the most effective.

Contextual Notes

Participants do not fully explore the implications of their proposed methods, and there may be missing assumptions regarding the geometric interpretation of the problem.

Who May Find This Useful

Students or individuals interested in linear algebra, vector geometry, and distance calculations in mathematical contexts may find this discussion relevant.

Student323
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TL;DR
Given the line L: x = (-3, 1) + t(1,-2) find all x on L that lie 2 units from (-3, 1).
Problem: Given the line L: x = (-3, 1) + t(1,-2) find all x on L that lie 2 units from (-3, 1).

I know the answer is (3 ± 2 / √5, -1 ± 4/√5) but I don't know where to start. I found that if t=2, x= (-5, 5) and the normal vector is (2, 1) but I am not sure if this information is useful or how to use it.
 
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Given a choice of t, can you write down the distance between L(t) and (-3,1)?
 
Student323 said:
Summary:: Given the line L: x = (-3, 1) + t(1,-2) find all x on L that lie 2 units from (-3, 1).

Problem: Given the line L: x = (-3, 1) + t(1,-2) find all x on L that lie 2 units from (-3, 1).

I know the answer is (3 ± 2 / √5, -1 ± 4/√5) but I don't know where to start. I found that if t=2, x= (-5, 5) and the normal vector is (2, 1) but I am not sure if this information is useful or how to use it.
You could intersect the line with a circle around (-3,1) with radius 2. For that set up the equation for the circle and use it for (x,y) on the line.
 
Another way is to step along the line until you get to a point that is ##2## units apart. Calculate the length between ##\binom{-3}{1}## and ##\binom{-3}{1}+t\cdot \binom{1}{-2}## which equals ##2##.
 

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