POV-Ray : Newsgroups : povray.general : arc length? Server Time: 29 Sep 2020 10:23:08 GMT
  arc length? (Message 1 to 6 of 6)  
From: Thomas de Groot
Subject: arc length?
Date: 9 Dec 2019 07:39:04
Message: <5dedfa18$1@news.povray.org>
Given a circle with known radius, what is the length of the arc segment 
formed between two radii with a known angle?

if you understand what I mean; that description feels awkward... :-/

-- 
Thomas


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From: Dick Balaska
Subject: Re: arc length?
Date: 9 Dec 2019 09:49:47
Message: <5dee18bb$1@news.povray.org>
Am 12/9/19 2:39 AM, also sprach Thomas de Groot:
> Given a circle with known radius, what is the length of the arc segment 
> formed between two radii with a known angle?
> 
> if you understand what I mean; that description feels awkward... :-/
> 

Wouldn't it be some fractional part of the circumference?

given degrees angle a=10, angle b=100 radius r=20

length = pi*r*2*(b-a)/360


-- 
dik
Rendered 46,077,465,600 of 49,882,521,600 pixels (92%)


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From: Thomas de Groot
Subject: Re: arc length?
Date: 9 Dec 2019 10:03:29
Message: <5dee1bf1@news.povray.org>
Op 09/12/2019 om 10:49 schreef Dick Balaska:
> Am 12/9/19 2:39 AM, also sprach Thomas de Groot:
>> Given a circle with known radius, what is the length of the arc 
>> segment formed between two radii with a known angle?
>>
>> if you understand what I mean; that description feels awkward... :-/
>>
> 
> Wouldn't it be some fractional part of the circumference?
> 
> given degrees angle a=10, angle b=100 radius r=20
> 
> length = pi*r*2*(b-a)/360
> 
> 

I didn't think of that! Thanks!! :-)

-- 
Thomas


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From: Alain Martel
Subject: Re: arc length?
Date: 10 Dec 2019 00:04:06
Message: <5deee0f6@news.povray.org>
Le 2019-12-09 à 02:39, Thomas de Groot a écrit :
> Given a circle with known radius, what is the length of the arc segment 
> formed between two radii with a known angle?
> 
> if you understand what I mean; that description feels awkward... :-/
> 

You only need to convert that angle into radiant, then multiply by the 
radius :

Just use the builtin macro :

#declare ArcLength = radians( AngleInDegree ) * Radius;


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From: Thomas de Groot
Subject: Re: arc length?
Date: 10 Dec 2019 07:27:19
Message: <5def48d7$1@news.povray.org>
Op 10/12/2019 om 01:04 schreef Alain Martel:
> Le 2019-12-09 à 02:39, Thomas de Groot a écrit :
>> Given a circle with known radius, what is the length of the arc 
>> segment formed between two radii with a known angle?
>>
>> if you understand what I mean; that description feels awkward... :-/
>>
> 
> You only need to convert that angle into radiant, then multiply by the 
> radius :
> 
> Just use the builtin macro :
> 
> #declare ArcLength = radians( AngleInDegree ) * Radius;
> 
> 

Initially, I had something like that in the back of my mind but was 
unable to move it to the front ;-)

Thanks indeed; I now have /two/ paths to achieve it.

-- 
Thomas


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From: Leroy
Subject: Re: arc length?
Date: 10 Dec 2019 20:40:03
Message: <web.5df0018cffbd966b6af142130@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:
> Le 2019-12-09 à 02:39, Thomas de Groot a écrit :
> > Given a circle with known radius, what is the length of the arc segment
> > formed between two radii with a known angle?
> >
> > if you understand what I mean; that description feels awkward... :-/
> >
>
> You only need to convert that angle into radiant, then multiply by the
> radius :
>
> Just use the builtin macro :
>
> #declare ArcLength = radians( AngleInDegree ) * Radius;

This is good to know!
I came across the other way on my own.
This way is shorter and less likely to have errors!


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