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Ash asked in Science & MathematicsMathematics · 4 months ago

7sinx=6 qurstion?

can someone check if my working is correct?

7sinx=6

sinx=6/7

x=sin^-1(6/7)

x= 58.997

5 Answers

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  • TomV
    Lv 7
    4 months ago
    Favorite Answer

    Remember the Unit Circle? "the angle whose (trig function) = x" usually has two answers in  the interval [0, 2π). You have provided one of those answers. Let's look for the other one:

    Recall: sin(π-x) = sin(π)cos(x) - cos(π)sin(x) = sin(x)

    For every angle, x ≠ kπ/2 where k is an odd integer, there is another angle, π-x, that has the same sine value. 

    Arcsin(x) is a function that returns values in the first or fourth quadrant only, it is up to you to find the second solution in the second or third quadrant. 

    You found arcsin(6/7) = 58.997, but sin(360°-58.997) is also equal to 6/7.

    The two values of x in the interval 0 ≤ x < 360 where 7sin(x) = 6 in the interval 0 ≤ x < 360° is:

    x₁ = 58.997° 

    x₂ = 180 - 58.997 = 121.003°

    There are an infinite number of angles coterminal with those two angles which also share the value of sine..

    [Use your calculator to verify that sin(58.997°) and sin(121.003°) are both equal to 6/7 within roundoff error. On my calculator they are the same within 2 x 10^-39, a very small difference indeed. The difference is due solely to using a finite decimal string for the angles. The more significant digits used for the angle measure, the smaller that difference will be.]

  • ?
    Lv 7
    4 months ago

    YES. Your work and answer are correct.

  • ?
    Lv 7
    4 months ago

     7 sin x = 6

     sin x = 6/7

     x = sin^-1(6/7)

     x = 58.997  

     You are correct

     line

     x-intercept | sin^(-1)(6/7) ≈ 1.0297  

     x = 59° (degrees)

  • rotchm
    Lv 7
    4 months ago

    Almost all correct. Just recall that

    sinx = 6/7 has two primary answers (and infinitely many answers).

     You gave one of the primary answers.

    The sin^-1 only gives you one. It is up to you to remember to find the other(s).

    So, whats the other possible result? [think of your trig circle].  

  • 4 months ago

    Other than labeling your answer with degrees (so it's not confused with radians, which then would not be the correct answer), this is correct.

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