Recent content by Charles Link

  1. Charles Link

    Undergrad Finding the minimum distance between two curves

    I would like to give a big thank you to @anuttarasammyak , @pasmith , @Gavran , and @DaveE for their inputs to this thread. I really think many could benefit by seeing how each of them solved this problem and reading through their solutions. Otherwise, I urge the reader to try and see if you...
  2. Charles Link

    Undergrad Finding the minimum distance between two curves

    @Gavran Very good. I think your Vieta calculation above might have come from Wolfram. My apologies if I am incorrect. When I recommended others to try it by hand above, (post 16), the version of the cubic I had, ## x^3-\frac{3x}{2} -\frac{3}{4}=0 ##, (from post 12 above), didn't need the...
  3. Charles Link

    Undergrad Finding the minimum distance between two curves

    @DaveE Excellent. In hindsight, your solution where you pointed out the inverted and translated symmetry of the two essentially identical parabolas is almost obvious, but I failed to recognize it. Thank you very much for your input. <3 <3 and your solution is in complete agreement with...
  4. Charles Link

    Undergrad Finding the minimum distance between two curves

    Please see the two Edits added to post 16 above. I think they may be useful.
  5. Charles Link

    Undergrad Finding the minimum distance between two curves

    @Gavran Very good=Excellent. :) You have an interesting approach where you translated the first curve by ## (a,b) ## until it made contact with the second curve at ## (x_1+a,y_1+b) ##. (To get this to occur you set the discriminant to zero=very clever). I checked over your calculations, and...
  6. Charles Link

    Undergrad Finding the minimum distance between two curves

    Just a couple additional comments: I thought I did pretty well by getting a numerical solution by writing out the partial derivative expressions and solving for ##x_1 ## and ## x_2 ## to first order about ## x=3/2 ##. The exact solutions given by @anuttarasammyak and @pasmith are really a...
  7. Charles Link

    Undergrad Finding the minimum distance between two curves

    @pasmith I think it should read ##-2(x_1+x_2-3)=0 ##. Otherwise, yes, very good=excellent. :) and I think I see where he got the wrong sign: Right before that he has ## y_2=(x+3)^2 ## where it should be a minus sign on the 3.
  8. Charles Link

    Undergrad Finding the minimum distance between two curves

    Yes, sometime I'm going to need to try Vieta's substitution on this cubic and see if I can get the same answers that Wolfram got. :) and perhaps @anuttarasammyak already identified the cubic in post 4 that needs to be solved. It may be simply solving ## 4a^3-6a-3=0 ## to get the ## x_1 ##...
  9. Charles Link

    Undergrad Finding the minimum distance between two curves

    For the calculation with the slopes mentioned in post 8, we have ## m=\frac{2-(4-a^2)}{3/2-a}=\frac{(3-a-3)^2-2}{3-a-3/2}## and these are both ## \frac{a^2-2}{3/2-a}=\frac{1}{2a} ## because of what @anuttarasammyak had previously mentioned in post 4 that comes from the first partial derivative...
  10. Charles Link

    Undergrad Finding the minimum distance between two curves

    @anuttarasammyak Perhaps you also noticed this already, but I find it interesting that with your exact solution, the slopes of the curves are precisely parallel, as they should be, at ## x_1= a ## and ## x_2=3-a ##, with slopes of ## -2 x_1 =-2a ## and ## 2(x_2-3)=-2a ##. Edit: I also believe...
  11. Charles Link

    Undergrad Finding the minimum distance between two curves

    @anuttarasammyak Thank you very much for your solution above. It is excellent. <3 <3
  12. Charles Link

    Undergrad Finding the minimum distance between two curves

    @anuttarasammyak We are going to need to look over your two partial derivative expressions carefully, because your solution is incorrect and not even in the right ballpark. I got, doing it all by hand with no computer that ## (x_1,y_1)=(1.43,1.96)##, and ##(x_2,y_2)=(1.57,2.04) ## for a...
  13. Charles Link

    Undergrad Finding the minimum distance between two curves

    @anuttarasammyak That's one part of what I did to solve it. Those two partial derivative expressions are really too clumsy to solve exactly. I used them though by getting an approximate ## x ## for where the two ## x ## values occur by first solving for the ## x ## where the vertical distance...
  14. Charles Link

    Undergrad Finding the minimum distance between two curves

    The other day a friend of mine gave me the above problem which I found rather interesting. I was able to get a numerical solution. I'll post how I solved it later in the thread. Others may want to try it and see what they come up with.
  15. Charles Link

    Undergrad Why Does Snow Pack Better Near the Melting Point?

    The above is a photo of a 3'0" snowman that I made today, Monday 3-16-26 in Chicago. It was several degrees below freezing so packing was very difficult but made possible by the warm ground below the snow where the temperature got up to 63 degrees yesterday.