$\"\"$

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Redraw the diagram:

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$\"\"$

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The center of mass $\"\"$ is $\"\"$ and $\"\"$ .

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Where $\"\"$ .

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Here, $\"\"$ is the total mass of the system.

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Calculate $\"\"$ :

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$\"\"$

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Calculate the centeroid:

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$\"\"$

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Calculate $\"\"$ :

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$\"\"$

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Calculate the centeroid:

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$\"\"$

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Symmentry $\"\"$ .

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Therefore the centroid is $\"\"$ and $\"\"$ .

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$\"\"$

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Find the value of $\"\"$ :

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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The center of mass is $\"\"$ .