Step 1 :

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(a)

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The trigonometric function $\"\"$ and $\"\"$ .

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Find $\"\"$ .

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Double-angle formula : $\"\"$ .

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If $\"\"$ , then $\"\"$ . (Since reciprocal identity : $\"\"$ )

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Solve for $\"\"$ .

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Pythagorean identity : $\"\"$ .

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$\"\"$

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$\"\"$

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Step 2 :

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(b)

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Find $\"\"$ .

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Double-angle formula : $\"\"$ .

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$\"\"$

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Step 3 :

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(c)

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Find $\"\"$ .

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Half-angle formula : $\"\"$ .

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$\"\"$

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$\"\"$ . (Since $\"\"$ )

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Step 4 :

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(c)

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Find $\"\"$ .

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Half-angle formula : $\"\"$ .

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$\"\"$

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$\"\"$ . (Since $\"\"$ )

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Solution :

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(a) The exact value of $\"\"$ .

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(b) The exact value of $\"\"$ .

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(c) The exact value of $\"\"$ .

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(d) The exact value of $\"\"$ .