The maximum and minimum values of cos6θ + si

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 Multiple Choice QuestionsMultiple Choice Questions

41.

For 0  P, Q  π2, if sinP + cosQ = 2, then the value of tanP + Q2 is equal to

  • 1

  • 12

  • 12

  • 32


42.

The value of

cos275° + cos245° + cos215° - cos230° - cos260° is

  • 0

  • 1

  • 12

  • 14


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43.

The maximum and minimum values of cos6θ + sin6θ  are respectively

  • 1 and 14

  • 1 and 0

  • 2 and 0

  • 1 and 12


A.

1 and 14

Let fθ = sin6θ + cos6θ fθ = sin2θ3 + cos2θ3            = sin2θ + sin2θsin4θ +cos4θ  - sin2θ . cos2θ                     a3 + b3 = a + ba2 + b2 - ab            = 1 . sin2θ + sin2θ2 - 3sin2θ . cos2θ            = 1 . 1 - 34 . 4sin2θ . cos2θ            = 1 - 34sin2θ2              sin2A = 2sinAcosA            = 1 - 381 - cos4θ      fθ = 1 - 38 + 38 . cos4θ - 1  cos4θ  1

 - 38  38cos4θ  38 58 - 38  58 + 38cos4θ  58 + 38 14  f(θ)  1      from Eq. (i)So, the maximum value is 1 and minimum value is 14


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44.

Let fθ = 1 + sin2θ2 - sin2θ. Then, for all values of θ

  • fθ > 94

  • f(θ) < 2

  • fθ > 114

  • 2  f(θ)  94


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45.

If P, Q and R are angles of an isosceles triangle and P = π2,  then the value of

cosP3 - isinP33 + cosQ + isinQcosR - isinR        + cosP - isinPcosQ - isinQcosR - isinR

  • i

  • - i

  • 1

  • - 1


46.

If fx = sinx + 2cos2x, π4  x  3π4. Then, f attains its

  • minimum at x = π4

  • maximum at x = π2

  • minimum x = π2

  • mamum at x = sin-114


47.

If sin2θ + 3cosθ = 2 then cos3θ + sec3θ is equal to

  • 1

  • 4

  • 9

  • 18


48.

Which of the following real valued functions is/are not even functions?

  • fx = x3sinx

  • f(x) = x2 cosx

  • fx = exx3sinx

  • f(x) = x - [x], where [x] denotes the greatest integer less than or equal to x.


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49.

Number of solutions of the equation tan(x) + sec(x) = 2cos(x), x [0, π] is

  • 0

  • 1

  • 2

  • 3


50.

If sin-1x +sin-1y + sin-1z = 3π2, then the value of x+ y9 + z91x9y9z9 is equal to

  • 0

  • 1

  • 2

  • 3


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