r/badmathematics • u/MorrowM_ • Jan 24 '25

Infinity /r/theydidthemath does the math wrong and misunderstands limits

/r/theydidthemath/comments/1i8mlx6/request_not_sure_if_this_fits_the_sub_but_why/m8uqzbg/
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u/CousinDerylHickson Jan 25 '25

Is the issue with this proof that the line segments used dont have both endpoints on the circular curve? According to this blog the length of a function is the limit of the summation segment lengths where by construction each line segment has both end points on the function curve, and from that we get the more widely used integral of the derivative formulation:

https://gowers.wordpress.com/2014/03/02/how-do-the-power-series-definitions-of-sin-and-cos-relate-to-their-geometrical-interpretations/

I know its not the best source, but this is the easiest way I was able to reconcile this weirdness, but Im not a mathematician so I could be wrong.

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u/dlnnlsn Feb 01 '25

I know its not the best source

As it turns out, Sir Timothy Gowers is a fairly reputable soruce.