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Trignometry

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6 May 2009 23:46:07 IST

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The number of integral values of k for which the equation 7cosx + 5sinx = 2k + 1 has solutions is __

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The number of integral values of k for which the equation 7cosx + 5sinx = 2k + 1 has solutions is ____? Options are 1) 4, 2) 8, 3) 10, 4) 112

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Akshay

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Joined: 27 Dec 2007

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6 May 2009 23:52:11 IST

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7cosx+5sinx=2k+1

observe that

max. integral value of the above function 7cosx+5sinx is 7

min. integral value is -7

therefore ur equation has a solution if

-7<=2k+1<=7

therefore

-4<=k<=3

so u have 8 integral values [-4,3]

Jammalamadaka

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6 May 2009 23:54:18 IST

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Thanks.

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