diameter calculation

[SillyOldDufferModerator @sillyoldduffer]

Posted by Michael Gilligan on 14/10/2019 15:02:46:

Posted by SillyOldDuffer on 14/10/2019 10:09:03:

[…]

For the record, my comments about extreme accuracy of calculation relate to the properties of Polar and Cartesian coordinates, not to Paul's original question.

By asking about a practical problem, Paul opened the door to some interesting mathematical solutions and related problems. I questioned the assertion that Polar Coordinates are intrinsically more accurate than Cartesian Coordinates by suggesting both systems are equivalent provided the calculations are done to a sufficiently large number of decimal places. (Not convinced this is correct and Michael has set me some homework!) I wasn't suggesting Paul or anyone else needs to do hard sums in their workshops!

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For the avoidance of doubt, Dave

What I intended to assert was not that “Polar Coordinates are intrinsically more accurate than Cartesian Coordinates”

But that ”for situations where Polar Coordinates properly specify the geometry, their use is intrinsically more accurate than a conversion to Cartesian Coordinates”

… It’s a subtle difference, but important.

MichaelG.

Arrgh! '… It’s a subtle difference, but important.' Certainly is. It's so easy to misread other people's posts! I am kicking myself…

Ta,

Dave

[Gary WoodingParticipant @garywooding25363]

Posted by duncan webster on 13/10/2019 23:55:52:

……….. but just to be pedantic, don't you need to use the cosine rule to find angle C to start the whole thing off rather than sin rule

Yes, you're right.

[Chris GunnParticipant @chrisgunn36534]

I am still struggling with the average of 1 and 2 being 2

Chris Gunn

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Chris Gunn on 17/10/2019 14:12:05:

I am still struggling with the average of 1 and 2 being 2

Chris Gunn

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I think he rounded 1.5 up … on the basis that 1 and 2 were expressed as integers.

MichaelG.

[Chris GunnParticipant @chrisgunn36534]

Thanks Michael, I knew I could rely on you.

CG

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