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Trignometry

Hot goIITian

 Joined: 4 Jun 2012 Post: 156
4 Jun 2012 19:32:15 IST
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cos 1 degree+cos 2 degree+cos 3 degree+.............+cos 180 degree=?
Engineering Entrance , JEE Main , JEE Main & Advanced , Mathematics , Trigonometry

cos 1 degree+cos 2 degree+cos 3 degree+.............+cos 180 degree=?

Cool goIITian

Joined: 3 Oct 2011
Posts: 82
4 Jun 2012 19:45:05 IST
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answer is -1 since cos180=-1 and remaining terms become 0

Blazing goIITian

Joined: 8 May 2012
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5 Jun 2012 20:47:38 IST
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how do u say so,sreedhar?

Blazing goIITian

Joined: 16 May 2012
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5 Jun 2012 20:56:15 IST
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vishwanathan refer graph of cos function from o to pie

Hot goIITian

Joined: 1 Jan 2012
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6 Jun 2012 10:10:47 IST
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cos1degree = -cos(180-1)degree = -cos179degree similarly cos2degree = -cos178degree ........so adding cos1degree + cos2degree + cos3degree.......+cos180degree =cos180degree = -1 so ans. is -1

New kid on the Block

Joined: 15 Jul 2012
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15 Jul 2012 13:52:16 IST
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The answer to the above question is zero as cos 90 degrees is 1 and cos 180 degrees is -1 and they cancel each other out

Blazing goIITian

Joined: 16 May 2012
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15 Jul 2012 19:49:55 IST
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@kalpana ........cos 90 degrees is not 1 its 0......plz refer the graphs of these functions for better understanding.....

New kid on the Block

Joined: 22 Sep 2012
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6 Oct 2012 20:55:33 IST
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cos 1 deg.*cos 2 deg*....*cos 90 deg.*... *cos 180 deg.=0 [because cos 90 deg. is 0]

New kid on the Block

Joined: 22 Sep 2012
Posts: 9
6 Oct 2012 21:08:33 IST
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sorry i have not seen the qu. properly ans is -1 as cos 180 degree is -1

New kid on the Block

Joined: 7 Oct 2012
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7 Oct 2012 12:02:36 IST
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ans is -1 as cos 180 degree=-1&lef terms will be cancelled out

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