Bafflers?

phrontister · 2012-09-25 05:10:12

Nice problem, btw. I enjoyed it.

bobbym · 2012-09-25 05:12:47

Yes, it was tricky to solve mathematically too. You did show me a trick or two with your use of geogebra. Thanks for working on the problem.

phrontister · 2012-09-25 05:28:34

I made a start on a mathematical solution to see if I could get to your 100 decimal-digit solution, but after struggling with it for a fair bit I let it go and solved it with Geogebra in a flash. So easy to use for something like this!

A very clever program, and I particularly like the great accuracy you can get with points etc that come alive when your mouse comes within cooee of them so that mouse clicks don't have to be pixel-perfect.

I found the area of the EFGH poly mathematically to umpteen decimal places:

I couldn't work out how to calculate segment areas to the same umpteen decimal places as the poly, and as it was getting too late I let it go and took the Geogebra road instead. When I'm more awake I might try again for the mathematical solution.

Last edited by phrontister (2012-09-25 05:38:35)

bobbym · 2012-09-25 05:40:21

Hi phrontister;

The solution I did was very tedious but it only requires some formulas and attention to detail. Let me know if you need some of it.

phrontister · 2012-09-25 05:51:38

Hi Bobby,

My poly area solution was also quite tedious. I had no idea as to how to find the area of an irregular polygon and so I googled it. I don't remember the method exactly now, but I think it used Heron's Formula and I added the two triangles together to get the answer in my previous post.

I'll sing out for help if I try the maths solution and get stuck. Thanks!

Bed nowzzzz.

bobbym · 2012-09-25 05:55:59

Hi;

You did the right thing. Google is your friend. It was how I got mine too.

anonimnystefy · 2012-09-25 06:55:51

phrontister wrote:

Hi Bobby,
My poly area solution was also quite tedious. I had no idea as to how to find the area of an irregular polygon and so I googled it. I don't remember the method exactly now, but I think it used Heron's Formula and I added the two triangles together to get the answer in my previous post.
I'll sing out for help if I try the maths solution and get stuck. Thanks!
Bed nowzzzz.

Hi phro

Maybe it was the shoelace method?

bobbym · 2012-09-25 07:04:41

I sure would like to see you duplicate my answer with one of your own.

phrontister · 2012-09-25 22:19:52

Hi stefy,

'shoelace method': "A technique for lifting oneself off the ground by pulling on one's own shoelaces, which, when mastered and applied properly, will guarantee a 100% failure rate."

No, I didn't use the shoelace method...I'm quite sure it was Heron's Formula because although I didn't keep my notes I recall some of the steps I used, and they're the same. I'd given up on the problem until I thought of using Geogebra.

I suppose I must have used an angle measurement from my Geogebra drawing as I think it's necessary for an area calculation of an irregular polygon.

bobbym · 2012-09-25 23:00:49

I suppose I must have used an angle measurement from my Geogebra drawing as I think it's necessary for an area calculation of an irregular polygon.

There is a formula for that too.

phrontister · 2012-09-26 12:49:13

Hi Bobby,

I'll see if I can find that formula.

I used too many steps in Geogebra to get to the result, and so I've revised it (see image).

Off to work now...

Last edited by phrontister (2012-09-26 22:16:16)

bobbym · 2012-09-26 20:10:25

Hi phrontister;

Very good! The formula for any polygon can be done with M using determinants.

phrontister · 2012-09-26 22:48:47

Hi Bobby,

Just found out you can link any spreadsheet cell to text in the Graphics view via the pull-down menu on the Objects button in the text box's popup window. Excellent! That means all text and numbers in the Graphics view and the spreadsheet of my project are now linked dynamically.

The formula for any polygon can be done with M using determinants.

Hmmm. This is all I know about determinants.

And this is what I know about matrices. Maybe the numeric content is somehow related to something, but I've yet to reach a conclusion about that.

I think I'll just stay with the Geogebra solution, Bobby. Time's a bit tight for me right now, anyway.

bobbym · 2012-09-26 23:02:06

Hi phrontister;

Okay, but if you ever need to do it to very high precision. Higher than geogebra, then M can do it for you.

Very nice vid!

bobbym · 2012-10-02 21:05:24

New Problem:

E is confronted with this problem on the job.

http://www.mathsisfun.com/puzzles/extra … ution.html

Her boss asks her to verify B's solution.

http://www.mathisfunforum.com/viewtopic … 04#p234004

A has argued with the boss that B's solution is not correct. A says there is another solution. The boss is not sure, he asks B, who says there is only one solution and he can prove it. The boss asks E to verify B's solution without using a computer program. She can use Alpha but he wants a math solution. Can you help E prove B is right?

anonimnystefy · 2012-10-02 21:10:53

Isn't the pair of equations from the other thread enough?

bobbym · 2012-10-02 21:28:18

Not for the boss and A. The boss knows that if there was another solution then those equations have to be wrong.

bobbym · 2012-10-13 12:27:37

New problem:

A die is rolled 3 times. What is the probability that the maximum value of the faces is 3?

A says) Man, that is so easy. I hardly even broke a sweat doing it. My probability must be getting better!

anonimnystefy · 2012-10-13 21:11:48

Are the dice different?

bobbym · 2012-10-13 21:18:09

One die is rolled 3 times.

anonimnystefy · 2012-10-13 21:23:57

Oh, okay then.

bobbym · 2012-10-13 21:29:25

Hi;

anonimnystefy · 2012-10-13 21:46:30

I have a feeling about what might be the next Baffler.

I will try coding a solution.

bobbym · 2012-10-13 21:54:25

You got it!

New problem:

A die is rolled 20 times. What is the probability that the maximum value of the faces is 3?

A says) I still think it is:

What is you answer?

anonimnystefy · 2012-10-14 00:29:55

I knew it!

This one is tougher...

Math Is Fun Forum

#901 2012-09-25 05:10:12

Re: Bafflers?

#902 2012-09-25 05:12:47

Re: Bafflers?

#903 2012-09-25 05:28:34

Re: Bafflers?

#904 2012-09-25 05:40:21

Re: Bafflers?

#905 2012-09-25 05:51:38

Re: Bafflers?

#906 2012-09-25 05:55:59

Re: Bafflers?

#907 2012-09-25 06:55:51

Re: Bafflers?

#908 2012-09-25 07:04:41

Re: Bafflers?

#909 2012-09-25 22:19:52

Re: Bafflers?

#910 2012-09-25 23:00:49

Re: Bafflers?

#911 2012-09-26 12:49:13

Re: Bafflers?

#912 2012-09-26 20:10:25

Re: Bafflers?

#913 2012-09-26 22:48:47

Re: Bafflers?

#914 2012-09-26 23:02:06

Re: Bafflers?

#915 2012-10-02 21:05:24

Re: Bafflers?

#916 2012-10-02 21:10:53

Re: Bafflers?

#917 2012-10-02 21:28:18

Re: Bafflers?

#918 2012-10-13 12:27:37

Re: Bafflers?

#919 2012-10-13 21:11:48

Re: Bafflers?

#920 2012-10-13 21:18:09

Re: Bafflers?

#921 2012-10-13 21:23:57

Re: Bafflers?

#922 2012-10-13 21:29:25

Re: Bafflers?

#923 2012-10-13 21:46:30

Re: Bafflers?

#924 2012-10-13 21:54:25

Re: Bafflers?

#925 2012-10-14 00:29:55

Re: Bafflers?

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