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The Incredible Puzzle Thread

posted by Klatuu on - last edited - Viewed by 3.4K users

Hi,

This is a thread to discuss some of your other favorite puzzles, riddles, brain teasers, armchair treasure hunts, etc.

To get started, here's an online puzzle hunt I've participated in before: Puzzlecrack. It's a week-long competition with clues given through the web page. Past competitions (and solutions) are still there for you to figure out.

Another similar one is Microsoft's College Puzzle Challenge.

Any other favorites?

-Klatuu

598 Comments - Linear Discussion: Classic Style
  • @Avistew said: EDIT: Here, I changed the picture to show what I mean.
    In my new picture, A isn't the center of the circle anymore.

    10pshoi.png

    In this case, it's obvious, since I wanted to show you what I meant. But how do you know that in the first picture, A is the center? What is the way to calculate it? Surely when you're just looking it's easy to get it wrong if it's just off the center, right?

    That's a quarter of a Elipse! You screw me!

    @Avistew said: @Avistew
    You then solve it geometrical.

    I totally forgot that, you right!

    Grab a rule, measure the lenght of AF (Let's say it's 10 cm) and then measure the lenght of AD (Let's say it's 12 cm). Then you say:

    10 cm -> 20 units
    12 cm -> X units

    Then x [units] = (12 [cm] * 20 [units]) / 10 [cm]

    That's only works if the Drawing has the correct proportions. If it's not, we're screwed again.

    @Avistew said: Okay, so you assume it's a quarter of a circle, without a real way to be sure of it. And due to the lack of information there probably isn't a way to be sure of it that doesn't involve getting out your compass. Did I get that right?

    Yes and no. If it's nobody telling you that's not a quarter of a circle, there's no reason I can't assume that, because it's nobody telling you either that drawing is correct at all. (That's always happen in a test the drawing are just demostrative, and normally you can't simple believe it's a circle because it's look like one.).

    If we don't assume is a quarter of a circle, I cannot figure out a way to do it. And, if you want to know for sure it's a quarter of a circle, bad luck, because not always the drawings had the correct proportions. If you don't telling me that drawing had the correct proportions and it's not just demostrative of the example, I still can assume is a quarter of a circle, unless the problem itself tell me is not a quarter of a circle.

    But, if the drawing has the correct proportions, you can use rule of three!

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    Tor

    Easy! In GIMP, just use the measure tool (shift-M) to find the length of AD. I get 320 pixels :p

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    Psy

    @GinnyN said: Now I'm curious for the other few specific locations!

    It has to do with the fact that terms like North, South, East, and West become undefined in specific locations. Consider if you were one mile north of the south pole; You'd go one mile south, there would be no east to travel (so you'd stand still) and then when you go one mile north, you could end up where you started- Or at an infinite number of other locations forming a circle 1 mile north of the pole.

    Alternately, if you're willing to say that you *start out* heading N/S/E/W, then you can do some tricks with crossing the north pole and having the directions all change names.

  • @GinnyN said: That's a quarter of a Elipse! You screw me!

    Okay, a quarter of an ellipse then. I'm so math-challenged that I just thought it was a bigger circle and off-center >.>

    @GinnyN said: I totally forgot that, you right!

    Grab a rule[...]

    Er, yeah, if I have a ruler I'll measure it directly and I'll know what size it is :p I was assuming you were supposed to calculate it.
    I guess I'm just making things complicated. You just assume it's a quarter of a circle. Like I did.

    I just was fairly sure math-people wouldn't just assume something like that without checking first in a more scientific way than their eyometre.

  • This is boring, a more interesting but still easy to answer question would be: How does a turtle (with some painting on her tail) has to move, in order to draw the picture (the lines and the circle) so that every distance is only walked once. Those interested in, also can offer a turtle code otherwise a picture showing the way is sufficient.

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    Psy

    If you're referring to the semicircle image that is being discussed, it can't be done.

  • Just want to point out that it doesn't have to be an ellipse, it CAN be a circle with A as not-the-center.

    Here is an example, and I showed where the center is, too.

    dcd37s.png

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