Re: sin x / x tends to 1...

Lee wrote:

> From this it follows that, *if you believe* that sin has a
> (non-zero) derivative *at all*, at any point, then its
> derivative is cos. Can that belief be justified without
> assuming the limit under consideration? I suspect it can,
> by further geometric argument using the helix
> parametrized by x \mapsto (cos(x), sin(x), x).

I agree. The slope of a circle can be found
without calculus. Thanks


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