Deriving an angle from three points

[Mark Swindell]

James,

Thanks for this, but starting the Turtle stack did not allow me to calculate the angle.  I got an error each time at "Start Turtle."  Is there a trick to making the library accessible to other stacks?

Mark

On Dec 16, 2009, at 8:08 AM, James Hurley wrote:

>> 
>> Message: 24
>> Date: Tue, 15 Dec 2009 22:21:47 -0800
>> From: Mark Swindell <mdswindell at cruzio.com>
>> Subject: Deriving an angle from three points
>> To: How to use Revolution <use-revolution at lists.runrev.com>
>> Message-ID: <B3725793-6274-4F53-91D2-3154D31F9CDF at cruzio.com>
>> Content-Type: text/plain;	charset=us-ascii
>> 
>> 40,116
>> 98,186
>> 132,118
>> 
>> How would one determine the angle created from three points, such as those above?
>> 
>> Thanks,
>> Mark
>> 
> 
> Mark,
> 
> Or even easier. Set the Turtle at the apex and get the angle of the other two points.
> 
> 
> on mouseUp
>   startTurtle --Initiates the turtle graphics library
>   penup
>   setxy 98,186 --The vertex
>   put direction(40,116) into A
>   put direction(132,118) into B
>   put B-A into dA
>   put abs(dA) & cr & abs(180 - dA)  into msg box
>   choose the browse tool
> end mouseUP
> 
> (Assuming your middle point is the apex of the angle you want.)
> 
> To run this you will need the TG library. Run this in the msg box
> 
> go url "http://www.jamesphurley.com/jhurleyFolder/TurtleGraphics.rev"
> 
> Jim Hurley
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