Todays Geometry Project .. A Regular Heptadecagon

[Bluechip]

Gentlemen ..

Draw, by Geometric Construction

A  17-Sided Regular Polygon..

OK. I'll let you watch it,    


http://upload.wikimedia.org/wikipedia/commons/d/d1/Regular_Heptadecagon_Inscribed_in_a_Circle.gif

Cute Eh??

Yes, OK, too much    about time I did something useful ...

Dave BC

[Rob.Wilson]

Hi Dave

You have way too much free time 

Regards Rob

[Bluechip]

Hi Dave

You have way too much free time 

Regards Rob

It's too soddin HOT ....

I wish it would snow again    .... 

Dave BC

[dsquire]

Gentlemen ..

Draw, by Geometric Construction

A  17-Sided Regular Polygon..

OK. I'll let you watch it,    


http://upload.wikimedia.org/wikipedia/commons/d/d1/Regular_Heptadecagon_Inscribed_in_a_Circle.gif

Cute Eh??





Yes, OK, too much    about time I did something useful ...

Dave BC

That great Dave if you only need 17 sides. I need one with 19 sides, can you help me out! 

Cheers 

Don

[mklotz]

A regular n-gon can be constructed with compass and straightedge only if n is the product of a power of 2 and any number of distinct Fermat primes.

Fermat number = 2^2^n + 1

Known Fermat primes = 2,5,17,257,65537

Constructible = 3, 4, 5, 6, 8, 10, 12, 15, 16, 17, 20, 24

Not constructible = 7, 9, 11, 13, 14, 18, 19, 21, 22, 23, 25

[Bluechip]

Don

It would appear that 19 is out!

Not that I would know, if it were not for Marv's intervention...

And, as someone who has just found out he cannot tell the difference between 3/8" & 7/16" despite a collection of micrometers and digital calipers, ...    

I am beginning to feel quite inadequate.

I think this is because I am ..

Must now find book entitled 'Ego Repairing for Dummies'

Dave BC

[dsquire]

Dave

I could say that I asked for 19 sides instead of 15 because I knew that it couldn't be done, but I won't. I didn't know either so I guess that we both learned something.

See, there now you have me feeling inadequate as well. Not to worry, if I really do need 19 sides or 15 sides I'll just go into Auto Cad and draw it out then measure it in what ever forum I want to use and to as much accuracy as I think I can handle. 

Cheers 

Don

[Stilldrillin]

Hmmmm........

Confused again........ Is it me? 

David D

[dsquire]

Hmmmm........

Confused again........ Is it me? 

David D

David D

Don't be confused on my behalf. The above reply was to Dave BC. Hope this helps. 

Cheers 

Don

[Bluechip]

Dave SD

We're all confused except Marv    I think ....

And me, .... 'cos I've given up 

Memo to self: Don't post any more animations 'cos you think they're cute ...

Stick to the stuff you ( think ? ) you know ..    and 

Not necessarily in that order, although it can be quite amusing  .. and character building for the survivors, if any.

Dave BC

[one_rod]

That's a great animation, but for me it brings back too many horrible memories. Hunched over a huge wooden drawing board, sometime in the 1970's, being taught Engineering Drawing the old fashioned way.
You were expected to remember a lot of those "Standard Constructions" and do them from memory in the exams.

I actually used to be quite proud of my drawing skills. Now I'm just glad I don't get to use them anymore.

The modern method is better.

Load AutoCad
Click on the Polygon  button.
Enter the number of sides.
Enter the diameter.
Specify Inscribed or Circumscribed.
Hit Return.

Job done, in less time than it takes to sharpen your pencil.   




one_rod.

[mklotz]

CAD is great if all you want is a quick solution to a problem but I have yet to meet anyone who learned anything about mathematics from a CAD program.  Sadly, these days everyone seems intent on actively avoiding learning anything about math.  It doesn't bode well for our collective future.

[Bluechip]

I quite like Math(s), sorry UK version.

Did it to O level at school, then some more at Tech.

Usual stuff for electrical engineering and whatnot. mostly Trig and the bits of Calculus that were relevant.

Then even did some more voluntarily in the late eighties/early ninties with the Open University. Little swot ...

I found it very absorbing, my only regret is not taking it further. No particlar advantage job wise, not at the age (45 ish) I was then anyway. Past it.

I shredded all the assignments about 2 yrs ago.

Culture shock that was.   

One tutor marked assignment on Matrix Algebra ..... got 96%   

Absolute gibberish . Yet it was my handwriting, and I don't remember sub-contracting the stuff out. So it must have been me !

Use it or lose it Eh ??

We're doomed Ah tell ye. DOOMED !!

Ah well, it all ends somewhere. In the Old Folk's Home, with somebody scraping my breakfast off my pullover ...

Dave BC


 
 

[z3t4]

Might have known that Gauss was behind it all.
Thanks for the post. Nice one!

John

[Bluechip]

Hi John

Manchester eh?

Introduce thassen then lad.

We like  piccys ....    and any amount of      you care to buy for us ...


Gauss ?? 

I know him!! 

British bloke, drives a little blue van with a picture of a flame on it ...

Gets around a bit, see him all over the place.

Wonder what he does ??

Dave BC 

[one_rod]

CAD is great if all you want is a quick solution to a problem but I have yet to meet anyone who learned anything about mathematics from a CAD program.  Sadly, these days everyone seems intent on actively avoiding learning anything about math.  It doesn't bode well for our collective future.

Got to say that I agree with you.
I'm sure the only reason we were taught those constructions was to drum into us the mathematical and geometric relationship between lines, angles and shapes. It can be hard stuff to learn, but once you have got it you have it forever and it comes in useful time after time.

However, in "real world" technical drawing you would hardly ever use it. If you want a nineteen-a-gon, it's much easier to make one by angle division or by using simple trig.

So I don't mind using computers to make my life easier, because I know that in a pinch I could do it without one.

As for the standard of maths teaching these days, I can't quite believe it.
My youngest son left school last year with a pretty good pass in his maths exam.
He started training as an apprentice electrician at the same place that I work. But it turns out that even the fairly simple maths required by a sparky were pretty much beyond him. I've ended up teaching him basic algebra almost from scratch, just so that he can do the job.

There's whole generations growing up now who wouldn't know where start, without machines to do their thinking for them.  As you say, makes you wonder about the future.




one_rod.

[mklotz]

The machine shop instructor at the junior college where we hold our metalworking club meetings laments the fact that he has to teach his incoming students how to read a ruler before he can begin teaching about measuring in the machine shop.

The schools don't teach math and they don't teach history.  Many of our youth think the (American) Civil War was the civil rights unrest of the 1960s.  The Vietnam war happened before WWII, a war we fought against the Russians.

They don't teach geography.  Switzerland is a Scandinavian country, there are kangaroos running wild in Austria and schoolkids in Brownsville, Texas can't name the country south of the United States.  (Brownsville, at the southern tip of Texas, is virtually surrounded by Mexico.)

And they don't teach English.  One only has to look at the quality of the writing on the Internet to appreciate the truth of that.

[Bernd]

And they don't teach English.  One only has to look at the quality of the writing on the Internet to appreciate the truth of that.

Boy Marv, I have to agree with you 100 percent on that one. Might want to add spelling too.

Really scary. Makes you wonder what the future holds. I don't even want to speculate.

Bernd