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A cube whose side length is 5 is shown below. Let P be on edge AB such that AP = 2, and let Q be on edge AE such that

AQ = 1. 

The plane passing through points C, P, and Q intersects DH at R. Find the length DR.

 

This has been asked here before:  https://web2.0calc.com/questions/cube-question-help, but the answer can't be seen because tinypic doesn't work, and I don't really think coordinate geo was meant for this problem. 

 

Thanks in advance for your help! smiley

 

Also, here is a hint:  Let the plane through C, P, and Q intersect the extension of DA at S. What can you say about the diagram? Which two-dimensional figures can you work with?

 Feb 13, 2021
edited by Guest  Feb 13, 2021
edited by Guest  Feb 13, 2021
edited by Guest  Feb 13, 2021
edited by Guest  Feb 13, 2021
 #1
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Triangles PQA and CRD are similar!!!

 

AQ / AP = DR / DC

 

1 / 2 = DR / 5

 

DR = 5/2

 Feb 13, 2021
 #2
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Hi Dragan! Thanks for your answer! Just wondering, how do you know PQA and CRD are similar? Thanks again! 

Guest Feb 15, 2021

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