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title: Law of Sines
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---
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## Law of Sines
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## Law of sines
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The Law of Sines simply states that:
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Sin(A) Sin(B)
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------ = ------
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a b
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Where "A" and "B" are angle measures, and "a" and "b" are their corresponding side lengths
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This law is used with triangles, when two angles and one side length are known, here is an example:
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The law of sines states that
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```
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sin(A) sin(B) sin(C)
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------ = ------ = ------
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a b c
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```
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where A, B and C are angles, and a, b and c are their corresponding (opposite) side lengths. This law is used with triangles, when two angles and one side length are known. For example, consider the triangle
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```
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b
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____________
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\ 75/
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@ -19,26 +19,21 @@ ____________
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\ /
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\30/
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\/
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In this problem, everything is defined except for "b," therefore, we can use the law of sines to find it. For this problem, I will
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refer to the corresponding angle and side as "A" and "a":
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Sin(A) Sin(B) Sin(75) Sin(30)
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------ = ------ ===> ------- = -------
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```
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In this (isoceles) triangle, we know everything except for b, the angle opposite B = 30°, therefore, we can use the law of sines to find it. With A = 75 and a = 6, we have
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```
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sin(A) sin(B) sin(75) sin(30)
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------ = ------ ===> ------- = -------
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a b 6 b
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For evaluating the Sines, I used a calculator. I can cross multiply the two sides of the equation, which evaluates as:
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6 * Sin(30)
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```
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Cross multiplying gives
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```
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6 * sin(30)
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b = -----------
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sin(75)
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```
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which simplifies to, approximately,
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Which comes out to
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b = 3.106
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#### More Information:
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<!-- Please add any articles you think might be helpful to read before writing the article -->
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<p align='center'>
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b ≈ 3.106
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</p>
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