$\"\"$

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Redraw the diagram :

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$\"\"$

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Consider the $\"\"$ with sides of $\"\"$ and $\"\"$

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The angle is $\"\"$ .

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Therefore the area of triangle is , $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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Therefore, the area of triangle is $\"\"$ .

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$\"\"$

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Observe the figure:

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As the three triangles $\"\"$ , $\"\"$ and $\"\"$ are equal , the total area of triangle is the threee times of anyone of the triangle.

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Therefore , total area is $\"\"$ .

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Total area is $\"\"$ .

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Hence total area is $\"\"$ .

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$\"\"$

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Total area is $\"\"$ .