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 2005-03-22, 21:48 #1 tinhnho   Jan 2005 158 Posts please help me, cal expert Find equivalent expressions( shortest is best) for the following do not involce any trig function or w or T. Thanks EX: sin(n*pi) =0 for all n and cos(n*pi)=(-1)^n for all n a) cos((2n+1)*pi/2) where n is a positive integer b) sin((2n+1)*w*T/2) where n is a positive integer c) cos(n*w*T/2) where n is a positive integer d) sin(2n+1)*pi/2) - cos(2n*pi/2) where n is a positive integer p/s: w is omega
 2005-03-22, 23:05 #2 tinhnho   Jan 2005 13 Posts i got a) =0 any one know how to get b and c ? thanks
 2005-03-23, 20:05 #3 ewmayer ∂2ω=0     Sep 2002 República de California 3×53×31 Posts I thought the whole point of homework was to figure it out for yourself...
 2007-09-24, 00:20 #4 Unregistered   23·23·31 Posts I thought the whole point of this forum is to help people with math homework?
 2007-09-24, 16:54 #5 akruppa     "Nancy" Aug 2002 Alexandria 2,467 Posts What are w and T? If those are just indeterminates, I think there's not much you can do to simplify b) and c). Alex
2007-09-24, 17:19   #6
R.D. Silverman

Nov 2003

22·5·373 Posts

Quote:
 Originally Posted by akruppa What are w and T? If those are just indeterminates, I think there's not much you can do to simplify b) and c). Alex
I believe that his post said that w = omega, for which I will assume he means
the first cardinal infinity. Now, since the domain of sin() and cos() is
the real numbers and omega is not a real number, it makes the expression(s)
gibberish.

2007-09-24, 17:20   #7
philmoore

"Phil"
Sep 2002
Tracktown, U.S.A.

111910 Posts

Quote:
 Originally Posted by Unregistered I thought the whole point of this forum is to help people with math homework?
The title of the thread would certainly lead people to assume that. Perhaps that was not what the moderator intended?

2007-09-24, 17:23   #8
R.D. Silverman

Nov 2003

22·5·373 Posts

Quote:
 Originally Posted by Unregistered I thought the whole point of this forum is to help people with math homework?
It is. But "help with homework" does not equal "do my homework for me".
To get help, you first need to show what you have done already with each
of the problems. Then we can guide you.

 2007-09-24, 19:12 #9 alpertron     Aug 2002 Buenos Aires, Argentina 22×337 Posts w = 2*pi*f = 2*pi/T so it should be easy to continue from here. But I think this help is too late for him since he posted his questions in 2005. Last fiddled with by alpertron on 2007-09-24 at 19:14
2007-09-24, 19:42   #10
davieddy

"Lucan"
Dec 2006
England

2×3×13×83 Posts

Quote:
 Originally Posted by Unregistered I thought the whole point of this forum is to help people with math homework?
Sounds like he is still interested. The dates explain why I have not
noticed this post before.

 2007-09-24, 21:55 #11 akruppa     "Nancy" Aug 2002 Alexandria 1001101000112 Posts Or it was someone else wondering about Ernst's response. In fact, I think the Homework Help forum was formed after 2005, and this old thread moved there. Alex

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