$\"\"$

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(a)

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The trigonometric function is $\"\"$ , $\"\"$ .

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Since $\"\"$ lies in quadrant I, $\"\"$ is also lies in quadrant I. $\"\"$

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(b)

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Find $\"\"$ .

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Using half - angle formulas: $\"\"$ .

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Substitute $\"\"$ in above formula.

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$\"\"$

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$\"\"$ (Since angle $\"\"$ is in quadrant I)

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$\"\"$

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Find $\"\"$ .

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Using half - angle formulas: $\"\"$ .

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Substitute $\"\"$ in above formula.

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$\"\"$

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$\"\"$ (Since angle $\"\"$ is in quadrant I)

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$\"\"$

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Find $\"\"$ .

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Using half - angle formulas: $\"\"$ .

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From Pythagorean theorem, $\"\"$ .

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Substitute $\"\"$ and $\"\"$ in above formula.

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$\"\"$

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$\"\"$ .

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$\"\"$

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(a) $\"\"$ lies in quadrant I.

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