Cos 1 Cos2 Cos3............Cos179
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[Post New] 11 Feb 2012 21:20:17 IST
   Subject: cos1.cos2.cos3...............cos179???? plss reply fast
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Ninad Dash (0)


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cos1.cos2.cos3...............cos179???? plss reply fast
    
[Post New] 11 Feb 2012 22:08:47 IST
   Subject: Cos 1 Cos2 Cos3............Cos179
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sathyaram (150)


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 We could use the formula:

 

 

 

cos(180-k)=-cos k

 

 

 

-cos 179 = cos (180-179)=cos 1.......

 

 

 

-cos 178 = cos (180-178)=cos 2 and so on....

 

We'll re-write the sum substituting the first terms, till cos 89, by their equivalents and we'll get:

 

 

 

-cos 179 -cos 178 -cos 177 - ... +cos 90 +...+cos 177 + cos 178 + cos 179.

 

 

 

 

 

Reducing the similar terms, we'll obtain:

 

 

 

 

S=0
 
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[Post New] 11 Feb 2012 22:50:53 IST
   Subject: Cos 1 Cos2 Cos3............Cos179
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Abhishek Bandiya (45)


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we don t need anything just see

s=cos1 cos2 cos3.......................cos179

but look now

s=cos1 cos2 cos3.............cos90..........cos179

as cos90=0

so     s=0
 
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[Post New] 15 Feb 2012 10:47:32 IST
   Subject: Cos 1 Cos2 Cos3............Cos179
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mr know all (0)


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0because cos90=0 and it will come between the series
 
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[Post New] 22 Feb 2012 00:40:05 IST
   Subject: Cos 1 Cos2 Cos3............Cos179
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YASHARTH SRIVASTAVA (0)


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 it will be 0 bec   cos 90 in between is o
 
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[Post New] 22 Feb 2012 00:41:47 IST
   Subject: Cos 1 Cos2 Cos3............Cos179
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YASHARTH SRIVASTAVA (0)


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 0 bec  cos 90 is 0
 
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[Post New] 22 Feb 2012 17:22:40 IST
   Subject: Cos 1 Cos2 Cos3............Cos179
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ARJUN AJAY (0)


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its 0......as cos90=0.

 
 
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