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tan(5pai/4)+tan(5pai/12)/1-tan(5pai/12)如何化简
题目详情
【tan(5pai/4)+tan(5pai/12)】/【1-tan(5pai/12)】如何化简
▼优质解答
答案和解析
利用诱导公式和逆用两角和的正切公式
∵ tan(5π/4)=tan(π/4)
∴ 【tan(5pai/4)+tan(5pai/12)】/【1-tan(5pai/12)】
= 【tan(π/4)+tan(5π/12)】/【1-tan(5π/12)】
=【tan(π/4)+tan(5π/12)】/【1-tan(π/4)tan(5π/12)】
= tan(π/4+5π/12)
= tan(8π/12)
=tan(2π/3)
=-tan(π/3)
=-√3
∵ tan(5π/4)=tan(π/4)
∴ 【tan(5pai/4)+tan(5pai/12)】/【1-tan(5pai/12)】
= 【tan(π/4)+tan(5π/12)】/【1-tan(5π/12)】
=【tan(π/4)+tan(5π/12)】/【1-tan(π/4)tan(5π/12)】
= tan(π/4+5π/12)
= tan(8π/12)
=tan(2π/3)
=-tan(π/3)
=-√3
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