已知
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為第二象限的角,
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為第三象限的角,
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。
(1)求
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的值;
(2)求

的值。
(1)
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(2)
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試題分析:解:(1)因為
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為第二象限的角,
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所以
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
所以
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(2)因為
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為第三象限的角,
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所以
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又
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
點評:主要是考查了三角函數(shù)的恒等變換的運用,屬于中檔題。
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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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