$\"\"$

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(a).

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The angle of elevation is $\"\"$ .

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Observee the figure :

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$\"\"$ .

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Where $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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(b).

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The angle of elevatin is $\"\"$ .

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Height of the pile : $\"\"$ .

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$\"\"$

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Substitute $\"\"$ and $\"\"$ in the above expression

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$\"\"$

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$\"\"$

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$\"\"$

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Therefore diameter is $\"\"$

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The diameter is $\"\"$ .

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$\"\"$

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(a). $\"\"$ .

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(b).The diameter is $\"\"$ .