若f(α)=[sin(π-α）cos(2π-α）tan(-α+π）]/[-tan(-α-π）sin（-π-α）]化简

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3 | 2011-11-30 23:01:40 | 显示全部楼层 |阅读模式

f(α)=[sin(π-α）cos(2π-α）tan(-α+π）]/[-tan(-α-π）sin（-π-α）]=[sinαcosα(-tanα)]/{tanα[-sin(π+α)}=-sinαcosαtanα/(tanαsinα)=-cosα...

千问 | 2011-11-30 23:01:40 | 显示全部楼层

利用三角函数的诱导公式的化简只需要记住一个口诀：奇变偶不变，符号看象限...

千问 | 2011-11-30 23:01:40 | 显示全部楼层

⑴f(α) = [sin(π-α)cos(2π-α)tan(-π-α)]/sin(-π-α)
= [sin(α)cos(-α)tan(-α)]/sin(α)
= cos(-α)tan(-α)
= cos(-α) * sin(-α) / cos(-α)
= sin(-α)
= ...

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