標題: I want proof!!! [打印本頁]

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作者: pigmi    時間: 2009-2-11 18:02     標題: I want proof!!!

I want proof of the following

lim       sinx/x  =1
x-->0

d/dx (sin x)=cos x

d/dx (cos x)=-sinx

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作者: 雅致裝飾    時間: 2009-2-11 19:50

for 1st one ,
u can use l'hosiptal rules or just expand sin x as x- x^3/3! + x^5 /5! ....

for 2nd and 3rd ,
just use first principle of derivative

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作者: 小神    時間: 2009-2-11 21:07

Go search the Web!

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