The number of integer values of k for which the equation 7cosx+5sinx=2k+1 has a solution is
A
4
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B
8
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C
10
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D
12
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Solution
The correct option is C8 The term 7cosx+5sinx belongs from −√74 to √74 Thus, −√74<2k+1<√74 ⇒2k+1>−9 or k>−5 and 2k+1<8 or k<3.5 So, we can have integral values of k from −4 to 3 i.e. 8 values.