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標題: 其實identity系咩? [打印本頁]

作者: billyconan 時間: 09-6-23 04:25 PM 標題: 其實identity系咩?

我完全5明law

作者: Naozumi 時間: 09-6-23 11:25 PM

簡單d講, identity左右兩邊在任何況下相等

最廢的identity: x + 1 = 1 + x
無論 x係乜,左右一定相等

冇咁廢的identity
1 - 1/x = (x - 1)/x

正常d的identity
sin x = cos (90 - x)

作者: Dennis_saidon 時間: 09-6-25 07:27 AM

原帖由 Naozumi 於 2009-6-23 11:25 PM 發表
簡單d講, identity左右兩邊在任何況下相等

最廢的identity: x + 1 = 1 + x
無論 x係乜,左右一定相等

冇咁廢的identity
1 - 1/x = (x - 1)/x

正常d的identity
sin x = cos (90 - x)

sin x = cos (90 - x) is called "co-function"
Recipical identity, Quotient identity and Pythagorean identity are the other three
they include cotx= 1/tanx, tanx= sinx/cosx, and cos^2x+sin^2=1 ...

i can explain more if u want

作者: davidmaths11 時間: 09-7-15 08:40 PM

一條special的identity
$\frac{x^{2}-5x+6}{x-3}=x-2$
雖然 L.H.S=R.H.S,但是當 x=3,L.H.S 是undefined

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