Trigonometry


  1. If tan θ = 1, then the value of
    8sin θ + 5cos θ
    is
    sin3θ - 2cos3θ + 7cos θ









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    tanθ = 1
    ⇒ θ = 45°

    8 sin θ + 5 cos θ
    sin3θ - 2cos3θ + 7 cosθ


    Correct Option: A

    tanθ = 1
    ⇒ θ = 45°

    8 sin θ + 5 cos θ
    sin3θ - 2cos3θ + 7 cosθ



  1. If tan θ = 1, then the value of
    8sin θ + 5cos θ
    is
    sin3θ - 2cos3θ + 7cos θ









  1. View Hint View Answer Discuss in Forum

    tanθ = 1
    ⇒ θ = 45°

    8 sin θ + 5 cos θ
    sin3θ - 2cos3θ + 7 cosθ


    Correct Option: A

    tanθ = 1
    ⇒ θ = 45°

    8 sin θ + 5 cos θ
    sin3θ - 2cos3θ + 7 cosθ




  1. If sin α sec (30° + α) = 1 (0 < a < 60°), then the value of sin α + cos 2α is









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    sinα
    = 1
    cos(30° + α)

    sinα
    = 1
    sin(90° - 30 - α)

    sinα
    = 1
    sin(60° - α)

    ⇒ sin α = sin (60° – α)
    ⇒ 2α = 60° ⇒ α = 30°
    ∴ sinα + cos 2α
    = sin 30° + cos 60°
    =
    1
    +
    1
    = 1
    22

    Correct Option: A

    sinα
    = 1
    cos(30° + α)

    sinα
    = 1
    sin(90° - 30 - α)

    sinα
    = 1
    sin(60° - α)

    ⇒ sin α = sin (60° – α)
    ⇒ 2α = 60° ⇒ α = 30°
    ∴ sinα + cos 2α
    = sin 30° + cos 60°
    =
    1
    +
    1
    = 1
    22


  1. If cos4 θ – sin4 θ = (2 / 3) , then the value of 2 cos²θ– 1 is









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    cos4 θ - sin4 θ =
    2
    3

    (cos2 θ + sin2 θ) (cos2 θ – sin2 θ)
    2
    3

    ⇒ cos2 θ - sin2 θ
    2
    3

    ⇒ 2cos2 θ - 1
    2
    3

    Correct Option: C

    cos4 θ - sin4 θ =
    2
    3

    (cos2 θ + sin2 θ) (cos2 θ – sin2 θ)
    2
    3

    ⇒ cos2 θ - sin2 θ
    2
    3

    ⇒ 2cos2 θ - 1
    2
    3



  1. If sin α + cos β = 2 (0° ≤ β ≤ α ≤ 90°), then sin (2α + β / 3) =









  1. View Hint View Answer Discuss in Forum

    sinα + cosβ = 2
    sinα ≤ 1 ; cosβ ≤ 1
    ⇒ α = 90° ; β = 0°

    = sin 60° =
    3
    2

    Also,
    cos
    α
    = cos 30° =
    3
    32

    Correct Option: B

    sinα + cosβ = 2
    sinα ≤ 1 ; cosβ ≤ 1
    ⇒ α = 90° ; β = 0°

    = sin 60° =
    3
    2

    Also,
    cos
    α
    = cos 30° =
    3
    32