tan1°tan2°+tan2°tan3°...+tan88°tan89°

来源:学生作业帮助网 编辑:作业帮 时间:2024/08/13 14:53:45
tan1°tan2°+tan2°tan3°...+tan88°tan89°
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tan1°tan2°+tan2°tan3°...+tan88°tan89°
tan1°tan2°+tan2°tan3°...+tan88°tan89°

tan1°tan2°+tan2°tan3°...+tan88°tan89°
∵tan(α-β)=(tanα-tanβ)/(1+tanαtanβ)
∴tanαtanβ=(tanα-tanβ)/tan(α-β) - 1
∴tan1°tan2°+tan2°tan3°...+tan88°tan89°
=(tan2°-tan1°)/tan1°+(tan3°-tan2°)/tan1°+...+(tan89°-tan88°)/tan1° -88
=(tan89°-tan1°)/tan1° - 88
=tan89°/tan1° -89
=tan²89° -89