Wednesday 25 May 2011

Two Ladders Puzzle

This puzzle is an old favourite of mine. It looks quite straightforward but it's not as easy as one might expect.

Two ladders are leaning against opposite walls in an alleyway. The bottom of each ladder is placed on the ground in the opposite corner. One ladder is 4m long, the other is 3m long. The height at which the two ladders meet is 1m.


Question: How far are the walls apart?
Posted by The Maths Geek at 10:16
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6 comments:

  1. Lucia25 May 2011 at 20:30

    nice one!

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  2. Aaron26 May 2011 at 15:58

    This comment has been removed by the author.

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  3. The Maths Geek27 May 2011 at 03:55

    @Aaron sqrt(143/17)+sqrt(143/10) = 6.68
    That would make both ladders fall down. Sorry :(

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  4. sapradhan27 May 2011 at 04:49

    assuming the walls are perpendicular to the floor

    http://www.wolframalpha.com/input/?i=solve+1%3D+1%2Fsqrt%289-d^2%29+%2B+1%2Fsqrt%2816-d^2%29

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  5. Peter27 May 2011 at 09:12

    solve: 1/sqrt(9-d*d) + 1/sqrt(16-d*d) = 1
    answer: d = 2.6032877544

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  6. AAd22 October 2011 at 14:46

    2 meters

    ReplyDelete

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