sin x / x tends to 1...



I've a question about the limit of sin x / x as x tends to zero. Of
course, it's 1 (I think), but I've never seen a satisfactory proof. The
proof I was given, and the proofs I can find in standard texts all rely
on knowing the area of a circular sector. However, to know the area of a
circular sector, one must know the area of a circle. All the derivations
I know for the area of a circle make use (either directly or indirectly)
on the sin x / x limit, and there lies my disatisfaction. Of course it's
easy to get the upper bound of one, and I'm happy to use the area
argument to establish the existance of a limit. However, it seems to be
surprisingly awkward to establish the obvious lower bounds (such as cos
x) using elementary arguments. Does anyone know a nice proof?

Regards,
--
Dr Darren Wilkinson
mailto:d.j.wilkinson@xxxxxxxxxxxxxxx
http://www.staff.ncl.ac.uk/d.j.wilkinson/
.



Relevant Pages

  • Re: sin x / x tends to 1...
    ... > I've a question about the limit of sin x / x as x tends to zero. ... > circular sector, one must know the area of a circle. ... > easy to get the upper bound of one, and I'm happy to use the area ...
    (sci.math)
  • Re: sin x / x tends to 1...
    ... > knowing the area of a circular sector. ... > must know the area of a circle. ... > or indirectly) on the sin x / x limit, ... there is no elementary proof that would satisfy you. ...
    (sci.math)
  • Re: sin x / x tends to 1...
    ... >I've a question about the limit of sin x / x as x tends to zero. ... >circular sector, one must know the area of a circle. ... >easy to get the upper bound of one, and I'm happy to use the area ...
    (sci.math)
  • Re: sin x / x tends to 1...
    ... >>I've a question about the limit of sin x / x as x tends to zero. ... >>circular sector, one must know the area of a circle. ... this precedes power series, ...
    (sci.math)
  • Re: sin x / x tends to 1...
    ... Darren J Wilkinson wrote: ... Since /x is even the result follows. ... > circular sector, one must know the area of a circle. ...
    (sci.math)