Archive for the ‘Identität’ Category

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useful identity

February 14, 2009

\frac {1}{ab} = \frac {1}{b - a} \left ( \frac1{a} - \frac1{b} \right )

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trig

November 12, 2008

\displaystyle\frac 1{\sin z}=\frac 1{\tan \frac{z}{2}}-\frac 1{\tan z}
\displaystyle \arcsin ({\cos x})+\arccos ({\cos x}) =\frac{\pi}{2}

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sin, cos, tan, sec, csc, ct ……

March 22, 2008

\displaystyle\sin\,(\pi\,x)\;=\;(\pi\,x)\prod_{k=1}^\infty\;\left(1-\dfrac{x^2}{k^2}\right)

http://www.mathlinks.ro/weblog.php?w=993 

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