The Equation of a Line in 3-Space

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SUMMARY

The discussion focuses on finding the parametric equations of a line that intersects both lines L1 and L2 at right angles. Line L1 is defined by the equation [x,y,z]=[4,8,-1] + t[2,3,-4], while line L2 is represented in symmetric form as (x-7)/-6 = (y-2)/1 = (z+1)/2. To derive the desired line, participants are advised to identify the direction vectors of L1 and L2, then compute the cross product to obtain a vector perpendicular to both. This perpendicular vector serves as the slope vector for the new line, which must also satisfy intersection conditions with L1 and L2.

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  • Understanding of parametric equations in three-dimensional space
  • Knowledge of vector operations, specifically cross products
  • Familiarity with line equations in both parametric and symmetric forms
  • Basic skills in solving systems of equations
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  • Learn how to compute the cross product of vectors
  • Explore methods for finding intersections of lines in three-dimensional space
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Find parametric equations of a line that intersect both L1 and L2 at right angles.
L1: [x,y,z]=[4,8,-1] + t[2,3,-4] L2: (x-7)/-6 = (y-2)/1 = (z+1)/2
 
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Stephen10523 said:
Find parametric equations of a line that intersect both L1 and L2 at right angles.
L1: [x,y,z]=[4,8,-1] + t[2,3,-4] L2: (x-7)/-6 = (y-2)/1 = (z+1)/2

Each line is parallel to a vector -- can you identity a vector to which L1 is parallel? and likewise for L2? (Hint: think about the "slope" vector).

Once you have two vectors, it should be easy to find a vector perpendicular to these two (cross product). Think of this new vector as the "slope" vector of the desired line. All that is left is to ensure that the desired line intersects L1 and L2.
 

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