$\"\"$

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Find the value of $\"\"$ .

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Draw a triangle $\"\"$ with angle $\"\"$ .

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$\"\"$

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Find the value of $\"\"$ by using the formula for $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$

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The value of $\"\"$ .