# Math: law of sines, hw help?

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- Engr. RonaldLv 71 month agoFavorite 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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- lenpol7Lv 71 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-MLv 71 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 sLv 71 month ago
sin A = 6 sin 30° / 7 = 3 / 7....trivial to work IF YOU know the Law of Sines

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