请问tanX怎么就＝1－cosx分之1啊。。 tanx怎么变成了x还有为什么最后一步就变为了2分之1 谢谢...
tanxcosx=1 \u8fd9\u4e2a\u662f\u5bf9\u7684\u5417\u4e3a\u4ec0\u4e48\u554atanxcosx=1 \u8fd9\u4e2a\u662f\u5bf9\u7684\u5417\u4e3a\u4ec0\u4e48\u554a
\u7b54\uff1a\u4e0d\u5bf9\uff01tanxcosx=(sinx/cosx)cosx=sinx\uff0c\u2234tanxcosx\u22601.
x->0
tanx ~ x
1-cosx ~ (1/2)x^2
tanx .(1-cosx) ~ (1/2)x^3
---------------------
lim(x->0) tanx .(1-cosx) /x^3
=lim(x->0) (1/2)x^3 /x^3
=1/2
是cosX分之一，还是1-cosX分之一？
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