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# Castle

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put one bridge over the corner and put another board on thar board so you decreased the length of the moat at the corners. so you pretty much made a "t" shape at the corner.

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lay one foot bridge across the corner of moat, then place another from center of that foot bridge to inside corner of moat

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Castle - Back to the Logic Puzzles

A square medieval castle on a square island was under siege. All around the island, there was a 10 metre wide water moat. But the conquerors could make foot-bridges only 9.5 metres long. Nevertheless a wise man was able to figure out how to get over the water. What do you think was his advice?

(There's a place on the other side to put the bridge against, not just a sheer wall. the water moat has square corners - that section of the moat is about 14.1 metres wide.)

Castle - solution

You can put one foot-bridge over one corner (thus a triangle is created). Then from the middle of this foot-bridge lay another foot-bridge to the edge (corner) of the castle. You can make a few easy equations confirming that this is enough.

could you not tie two ends together to span the moat like a folding ladder?

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you place one of the bridges on a corner forming a right triangle with the legs, the shore and the hypotenuse, the ladder then take another bridge from the middle of the first bridge over to the pint on the other side of the moat. the distance you gain from the first bridge shortens it enough for the second to span it.

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I would guess that the moat isn't a completely straight line so a possible example is this:

Bear in mind its 10m at the top, so you must throw the wood down halfway (appr.) and then climb up a bit!

Solved!

BRIDGE_BRAINTEASER.bmp

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• 3 weeks later...

Why do they need to get inside if they can canapult it?

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I have a Question ; Why do the conquerers need to get to the other side of the moat . They have already won the battle. Why not fill the moat in with the dead bodies of the defeated enemy then walk across .

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Castle - Back to the Logic Puzzles

A square medieval castle on a square island was under siege. All around the island, there was a 10 metre wide water moat. But the conquerors could make foot-bridges only 9.5 metres long. Nevertheless a wise man was able to figure out how to get over the water. What do you think was his advice?

(There's a place on the other side to put the bridge against, not just a sheer wall. the water moat has square corners - that section of the moat is about 14.1 metres wide.)

Castle - solution

You can put one foot-bridge over one corner (thus a triangle is created). Then from the middle of this foot-bridge lay another foot-bridge to the edge (corner) of the castle. You can make a few easy equations confirming that this is enough.

I hate to belinger a dead issue but I don't think your solution works. I don't understand the math behind your equations but I plugged the dimensions into a scale drawing program and the only way your diagonal solution can work is if the boards are completely unsupported at the ends. The dimensions can meet (perhaps a better word would be span) the required distances but they are not supported and will fall in the moat. Hopefully I'm not missing something obvious.

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I hate to belinger a dead issue but I don't think your solution works. I don't understand the math behind your equations but I plugged the dimensions into a scale drawing program and the only way your diagonal solution can work is if the boards are completely unsupported at the ends. The dimensions can meet (perhaps a better word would be span) the required distances but they are not supported and will fall in the moat. Hopefully I'm not missing something obvious.

Yeah... I guess I made up a word (belinger). Sorry about that. Not sure where it came from.

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you just have to put a foot bridge across the bridge and then just put one in the middle of it and it would work

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Doesn't the bridge float. Use it like a boat.

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• 2 weeks later...

i'd buy a 10m+ ladder from ye olde b&q and crawl across it using it as a bridge

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• 2 weeks later...
I would just put 1 bridge across the corner and the other from the middle of that bridge the edge of the island. Like so:

that was my idea too ....

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• 3 months later...

or u could put the ladders in half a foot closer

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• 1 month later...

well, you could have the 9.5 foot long board and have a person have his legs tied to the board (maybe a captive) and then the army could walk across the person and the board, i am probably wrong

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• 10 months later...

What If I lay the footbridge diagonally. My drawing may not be on scale, but this could do the job. I hope.

footbridge.bmp

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• 2 months later...

Hi guys,

I just stumbled over this brain teaser and was amused about the entire list of posts discussing the various solutions.

Here is another one that is “self stabilizing” and doesn’t require people to stand on one end to make it work!

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• 1 month later...

Hi guys,

I just stumbled over this brain teaser and was amused about the entire list of posts discussing the various solutions.

Here is another one that is “self stabilizing” and doesn’t require people to stand on one end to make it work!

You could not assemble this unless someone were on the other side...

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• 1 year later...

How about using the foot bridge as a pole, and use it to jump over the moat?

Or find something big and sturdy and place the footbridge accross it like a see-saw. Then, put a light guy on the end furthest away from the castle, and a fat guy on the other end, When the fat guy jumps on his end, the light guy would catapult to the other side! And, since we don't know how wide it is, you could maybe rotate the footbridge and walk across that way.

Or, make a guy hold the bridge, diagnally like a slide, and have the rest of the people climb up him and slide across. Of course, that guy wouldn't go, but then he could get paid for nothing!

Or, since they can't return empty-handed, just make their own village and become rich merchants.

Or, if the king ordered for a group of jesters, the assassins could kill the origonal jesters, steal their clothing, and get admitted into the castle!

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