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? asked in Science & MathematicsMathematics · 8 years ago

2sin^2x = sinx + 1; 0<or=x<or=2pi?

please help me I need to finish this before school starts and I dont' know how to do it.

3 Answers

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  • 8 years ago
    Favorite Answer

    Here 2 sin ² x = sin x + 1

    2 sin ² x - sin x - 1 = 0.

    (2 sin x + 1)(sin x - 1) = 0

    2 sin x + 1 = 0 AND sin x - 1 =0

    so

    sin x = -1/2 and sin x = 1

    so

    x = π/2 (in case of sin x = 1)

    and

    x= 7π/6, 11π/6 (or you can write it as - π/6 .) [ in case of sin x = -1/2]

  • 8 years ago

    2sin^2x = sinx + 1

    2sin^2(x) - sin(x) - 1 = 0

    [2sin(x) + 1][sin(x) - 1] = 0

    2sin(x) + 1 = 0, sin(x) - 1 =0

    2sin(x) = - 1, sin(x) = 1

    sin(x) = - 1/2

    x = - π/6. 7π/6, π/2, answer//

  • ?
    Lv 7
    8 years ago

    (2sinx+1)(sinx-1) = 0

    sinx = -1/2 and 1

    x = pi/2, 7pi/6, 11pi/6

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