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If p≤(cos2x+6sinx-1)≤q, then (p,q)= a.(-8,4) b.(4,8) c.(-4,8) d.none of these

If p≤(cos2x+6sinx-1)≤q, then (p,q)=


a.(-8,4)


b.(4,8)


c.(-4,8)


d.none of these

Grade:12th Pass

1 Answers

Ashwin Muralidharan IIT Madras
290 Points
10 years ago

Hi Menka,

 

Form a Quadratic in sinx, by the substitutung for cos2x in terms of sin^2 x.

 

So you have p≤6sinx-sin^2 x≤q.

 

Minimum value obtained by substituting sinx=-1 and max value obtained by sinx=1

So p=-8 and q=4.

Which is option (A) but with closed brackets.

 

Hope that helps.

 

Best Regards,

Ashwin (IIT Madras).

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