极限计算的一题lim 1-cosaa→0 ----------····asina我算了n遍答案都是1.与参考答案不一致.有米人可以帮忙.我的计算过程是这样的:lim`````1-cosa``````sin2a+cos2a-cosa````sina```````cosa(cosa-1)a→0 -----------·=
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![极限计算的一题lim 1-cosaa→0 ----------····asina我算了n遍答案都是1.与参考答案不一致.有米人可以帮忙.我的计算过程是这样的:lim`````1-cosa``````sin2a+cos2a-cosa````sina```````cosa(cosa-1)a→0 -----------·=](/uploads/image/z/7657499-11-9.jpg?t=%E6%9E%81%E9%99%90%E8%AE%A1%E7%AE%97%E7%9A%84%E4%B8%80%E9%A2%98lim+1-cosaa%E2%86%920+----------%C2%B7%C2%B7%C2%B7%C2%B7asina%E6%88%91%E7%AE%97%E4%BA%86n%E9%81%8D%E7%AD%94%E6%A1%88%E9%83%BD%E6%98%AF1.%E4%B8%8E%E5%8F%82%E8%80%83%E7%AD%94%E6%A1%88%E4%B8%8D%E4%B8%80%E8%87%B4.%E6%9C%89%E7%B1%B3%E4%BA%BA%E5%8F%AF%E4%BB%A5%E5%B8%AE%E5%BF%99.%E6%88%91%E7%9A%84%E8%AE%A1%E7%AE%97%E8%BF%87%E7%A8%8B%E6%98%AF%E8%BF%99%E6%A0%B7%E7%9A%84%EF%BC%9Alim%60%60%60%60%601-cosa%60%60%60%60%60%60sin2a%2Bcos2a-cosa%60%60%60%60sina%60%60%60%60%60%60%60cosa%28cosa-1%29a%E2%86%920+-----------%C2%B7%3D)
极限计算的一题lim 1-cosaa→0 ----------····asina我算了n遍答案都是1.与参考答案不一致.有米人可以帮忙.我的计算过程是这样的:lim`````1-cosa``````sin2a+cos2a-cosa````sina```````cosa(cosa-1)a→0 -----------·=
极限计算的一题
lim 1-cosa
a→0 ----------
····asina
我算了n遍答案都是1.与参考答案不一致.有米人可以帮忙.
我的计算过程是这样的:
lim`````1-cosa``````sin2a+cos2a-cosa````sina```````cosa(cosa-1)
a→0 -----------·=-------------------------`=------- + ------------------
`````````asina````````````asina```````````a```````````sina*a
````````````sina``````````
因为lim=--------=1,lim=tana=0
``````a→0``````a```````a→0
所以原式为1
16:56的回答的第二步- 是怎么到第三部的?
极限计算的一题lim 1-cosaa→0 ----------····asina我算了n遍答案都是1.与参考答案不一致.有米人可以帮忙.我的计算过程是这样的:lim`````1-cosa``````sin2a+cos2a-cosa````sina```````cosa(cosa-1)a→0 -----------·=
lim(a->0)(1-cosa)/(asina)
=lim(a->0)(1-cosa)'/(asina)'
=lim(a->0)(sina)/(sina+acosa)
=lim(a->0)( sina / a )/( sina / a + cosa)
=1/(1+1)=0.5
是1/2吧
(1-cosa)/(asina)=tan(a/2)/a
应用洛比达法则
[sec^2(a/2)]/2
答案是1/2