tanh_x_미분_증명

Difference between r1.3 and the current

@@ -7,5 +7,10 @@
$=\frac{\cosh^2x-\sinh^2x}{\cosh^2x}$
$=\frac1{\cosh^2x}$
$=\operatorname{sech}^2 x$
 
KWs:
hyperbolic tangent derivative proof
쌍곡탄젠트 미분 증명
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Up: [[여러가지증명]]


정리

$\displaystyle \frac{d}{dx}\tanh x=\frac{1}{\cosh^2 x}=\operatorname{sech}^2 x$

증명

$\displaystyle (\tanh x)'=\left(\frac{\sinh x}{\cosh x}\right)'$
$\displaystyle =\frac{(\sinh x)'\cosh x-\sinh x(\cosh x)'}{\cosh^2 x}$
$\displaystyle =\frac{\cosh^2x-\sinh^2x}{\cosh^2x}$
$\displaystyle =\frac1{\cosh^2x}$
$\displaystyle =\operatorname{sech}^2 x$

KWs:
hyperbolic tangent derivative proof
쌍곡탄젠트 미분 증명