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Topic: Re: Calculator
Replies: 25   Last Post: Aug 9, 1997 4:54 PM

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Dave Slomer

Posts: 244
Registered: 12/6/04
Re: Calculator
Posted: Aug 1, 1997 8:47 AM
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> From: Joshua Zucker <zucker@csli.Stanford.EDU>
> To: Multiple recipients of list <ap-calc@ets.org>
> Subject: Calculator
> Date: Thursday, July 31, 1997 4:45 PM
>
> log(-1) gives an answer? How does it do that? (2n+1)*i*pi ?
>
> Or does it just give i*pi as the only answer. And if so, what about
> sqrt of complex numbers? Does it give sqrt(i) = approx .707 + .707 i
> or does it give both the + and - answer?


In the realm of complex analysis, all kinds of neat relationships exist.
The first below is easily explainable via power series. In particular:

e^(a+b*i)=e^a*(cos b + i sin b)

If b>0, then ln(a+b*i)=ln(sqrt(a^2+b^2))+(arctan(a/b)+pi/2)i (and a similar
mess if b<0)

And lots more.

For instance, arcsin(2) = pi/2 + i ln(sqrt(3)+2).

Dave Slomer
AP Calculus and Computer Science Teacher
Winton Woods HS, Cincinnati, OH 45240





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