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The trigonometric equation is $\"\"$ and $\"\"$ .

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Reciprocal identity: $\"\"$ .

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If $\"\"$ , then $\"\"$ .

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Find the value $\"\"$ .

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Pythagorean identity: $\"\"$ .

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$\"\"$

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Since $\"\"$ , $\"\"$ .

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(a) Find $\"\"$ .

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

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

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$\"\"$

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(b) Find $\"\"$ .

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

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

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$\"\"$

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(c) Find $\"\"$ .

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

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

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$\"\"$

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Since $\"\"$ is negative and $\"\"$ is negative.

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Thus, $\"\"$ lies in third quadrant.

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Therefore, $\"\"$ and $\"\"$ .

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In $\"\"$ sine function is positive.

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$\"\"$ .

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(c) Find $\"\"$ .

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

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

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$\"\"$

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Here $\"\"$ .

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$\"\"$ .

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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 $\"\"$ .