maths
回答 (2)
2009-06-22 3:32 am
✔ 最佳答案
(sin x)^2 + (cos x)^2 = 1Divide both side by (cos x)^2, then
(tan x)^2 + 1 = (sec x)^2= 1/ [(cos x)^2]
So sin x cos x [1 + (tan x)^2 ]
= sin x cos x { 1/ [(cos x)^2] }
= (sin x) / (cos x)
= tan x
2009-06-22 3:49 am
左方=sinx cosx ( 1+ tan2x )
= sinx cosx (1/cos2x)
=sinx/cosx
=tanx
=右方
∴sinx cosx ( 1+ tan2x )= tanx是恒等式
= sinx cosx (1/cos2x)
=sinx/cosx
=tanx
=右方
∴sinx cosx ( 1+ tan2x )= tanx是恒等式
收錄日期: 2021-04-23 20:39:06
原文連結 [永久失效]:
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