Math: law of sines, hw help?

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  • 1 month ago
    Favourite answer

    ..a............b

    -------- = -------

    sin(A)......sin(B)

    ..6.............7

    -------- = ----------

    .sin(A)....sin(30)

    6sin(30) = 7sin(A)

    6(1/2) = 7sin(A) note sin(30) = 1/2 according to the unit circle

    3 = 7sin(A)

    sin(A) = 3/7  Answer//

    Answer is A. 3/7

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  • 1 month ago

    First of all this is NOT the law of sines, but the 'Sine Rule , which is a/SSinA = b/SinB'. 

    Substituting 

    6/SinA = 7/Sin30 

    Algebraically rearrange 

    SinA = 6Sin30 / 7 

    Remember Sin30 = 1/2 ; substitute. 

    SinA = 6(1/2) / 7 

    SinA = 3/7  

    Then answer is 'A' 

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  • Bill-M
    Lv 7
    1 month ago

    a/sin A = b/sin B

    replace with known values:

    6 / sin A = 7/sin 30

    Cross Multiply

    7sin A = 6sin30

    sin A = 6sin30/7

    sin30 = 0.5

    sin A = 6*.5 / 7

    sin A = 3/7

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  • ted s
    Lv 7
    1 month ago

    sin A = 6 sin 30° / 7 = 3 / 7....trivial to work IF YOU know the Law of Sines

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