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(a)

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Write $\"\"$ as a function of $\"\"$ .

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Observe the figure:

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$\"\"$ .

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$\"\"$

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$\"\"$ .

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(b)

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The speed of plane is $\"\"$ .

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$\"\"$ .

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Find $\"\"$ .

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$\"\"$

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Apply derivative on each side with respect to $\"\"$ .

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$\"\"$

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Derivative of inverse trigonometric functions: $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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Find the value of $\"\"$ when $\"\"$ :

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

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$ .

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Find the value of $\"\"$ when $\"\"$ :

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

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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(a) $\"\"$ .

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(b) When $\"\"$ , $\"\"$ .

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When $\"\"$ , $\"\"$ .