$\"\"$

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a). $\"\"$ .

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The trigonometric functions are $\"\"$ . $\"\"$

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Cofunction identity : $\"\"$ ).

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$\"\"$ $\"\"$

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b). $\"\"$

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The trigonometric functions are $\"\"$ .

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To find $\"\"$ .

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Cofunction identity : $\"\"$

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$\"\"$

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$\"\"$ . $\"\"$

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c). $\"\"$ .

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Trigonometric identity : $\"\"$ .

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$\"\"$ . $\"\"$

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d). $\"\"$ .

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Reciprocal identity : $\"\"$ .

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$\"\"$ . $\"\"$

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Therefore, (a). $\"\"$ ,

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