Draw a 145 degree angle without a protractor

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Draw a 145 degree angle without a protractor

Postby 145 » Thu Mar 24, 2011 9:57 am

How to draw a 145 degree angle without a protractor?
It is easy to draw 150 degree but how to draw a 145 degree angle?
145
 

Re: Draw a 145 degree angle without a protractor

Postby leesajohnson » Wed Nov 09, 2016 6:45 am

How to show here I don't understand.

leesajohnson
 

Re: Draw a 145 degree angle without a protractor

Postby Guest » Wed Nov 09, 2016 8:29 am

It is impossible to draw a 145 degree angle using only a compass and straight edge.

If it was possible you could construct an angle of 5 degrees by using the construction for 150 degrees, then by combining 4 lots of 5 degree angles you could get an angle of 20 degrees, which has been famously shown to be not constructible in the proof that (general) trisection of angles is impossible.

It is possible to get 145 degrees but you have to employ some additional tool, see
https://en.wikipedia.org/wiki/Angle_tri ... er_methods
using these methods you can trisect 60 degrees, to get 20 degrees, then bisect twice to get 5 degrees, and add multiple lots of 5 degrees together to get 145 degrees.

Hope this helped,

R. Baber.
Guest
 

Re: Draw a 145 degree angle without a protractor

Postby Guest » Wed Nov 09, 2016 11:40 am

I think all you need to do is take an A$ page of paper, fold it in half....gives you A5 size.

Fold the A5 diagonally ...this gives you 35 degrees...... 180 - 35 = 145.

Done
Guest
 

Re: Draw a 145 degree angle without a protractor

Postby Guest » Wed Nov 09, 2016 11:41 am

take an A$ page of paper

........should be A4 page of paper
Guest
 

Re: Draw a 145 degree angle without a protractor

Postby Guest » Thu Nov 10, 2016 6:54 am

Folding by the method described gets you an angle of 35.264... degrees not 35 degrees.

You can get 145 degrees by folding but it is a lot more complicated then just folding an A4 sheet twice.

R. Baber.
Guest
 

Re: Draw a 145 degree angle without a protractor

Postby Guest » Thu Nov 10, 2016 7:38 pm

Yes, OK, accepted, but.....The question was to draw an angle, and that need accuracy. Every time you fold paper and add it to something already folded accuracy soon disappears.
Attachments
Angle145.JPG
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Guest
 

Re: Draw a 145 degree angle without a protractor

Postby Guest » Sun May 08, 2022 10:51 am

Thanks for post
Guest
 

Re: Draw a 145 degree angle without a protractor

Postby Guest » Mon May 16, 2022 6:37 pm

:evil: :evil: :evil:
Guest
 


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