show f' is continuous

[w huang]

Let f(x) = (sin x)/x if x /= 0
. . f(0) = 0.

Show f' is continuous.
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online CAS www.mathHandbook.com show f' is continuous in graph by http://www.mathyun.com/input/?guess=d(sinc(x))

[Dr Huang]

pls use www.mathHandbook.com instead is mathyun.com