View single post by Helmut
 Posted: Sat Jan 25th, 2020 09:53 am
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Helmut



Joined: Sun Feb 17th, 2013
Location: Friedberg, Germany
Posts: 1181
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What else than 21.95", to be exact, would you have expected?


You can calculate that Radius within 2 minutes,

when you just look at the geometrical dependencies.


Look at the drawing given in the link:

x/L = L/2R = sin(D/2)

So x=L*sin(D/2) =2R*sin²(D/2) or R= x/(2*sin²(D/2))


Take your values:

3/4" = 19mm, D=15°, sin(D/2) = 0.13, sin²(D/2)=0.017

Insert in formula for R: R = 19/(2*0.017) = 558.8mm = 22"


That's all.



Addendum:

To calculate y, just remember that x/y = tan(D/2) and so y= x/tan(D/2)

In our case, y= 0.75/0,132 = 5.7

As easy as pie.




____________________
Regards, H.
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