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Old 2005-03-22, 21:48   #1
tinhnho
 
Jan 2005

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Default 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
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Old 2005-03-22, 23:05   #2
tinhnho
 
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i got a) =0

any one know how to get b and c ? thanks
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Old 2005-03-23, 20:05   #3
ewmayer
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I thought the whole point of homework was to figure it out for yourself...
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Old 2007-09-24, 00:20   #4
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I thought the whole point of this forum is to help people with math homework?
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Old 2007-09-24, 16:54   #5
akruppa
 
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"Nancy"
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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
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Old 2007-09-24, 17:19   #6
R.D. Silverman
 
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Quote:
Originally Posted by akruppa View Post
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.
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Old 2007-09-24, 17:20   #7
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Quote:
Originally Posted by Unregistered View Post
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?
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Old 2007-09-24, 17:23   #8
R.D. Silverman
 
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Quote:
Originally Posted by Unregistered View Post
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.
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Old 2007-09-24, 19:12   #9
alpertron
 
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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
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Old 2007-09-24, 19:42   #10
davieddy
 
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Quote:
Originally Posted by Unregistered View Post
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.
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Old 2007-09-24, 21:55   #11
akruppa
 
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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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