$\"\"$

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Draw the perpendicular distance from $\"\"$ .

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Redraw the diagram :

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$\"\"$

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Law of sines for triangle $\"\"$ : $\"\"$ .

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Consider $\"\"$ .

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Substitute $\"\"$ and $\"\"$ and $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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The sum of angles in triangle is $\"\"$ .

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Sustitute $\"\"$ and $\"\"$ .

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$\"\"$

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$\"\"$ .

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From the figure :

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$\"\"$

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$\"\"$

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$\"\"$ .

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Therefore, the perpendicular distance from $\"\"$ is $\"\"$ .

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$\"\"$

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$\"\"$ .

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The perpendicular distance from $\"\"$ is $\"\"$ .