Difference between revisions of "Taylor series of cosine"

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<strong>[[Taylor series of cosine|Theorem]]:</strong> The following [[Taylor series]] holds:
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<strong>[[Taylor series of cosine|Theorem]]:</strong> Let $z_0 \in \mathbb{C}$. The following [[Taylor series]] holds:
$$\cos(z)= \displaystyle\sum_{k=0}^{\infty} \dfrac{(-1)^k z^{2k}}{(2k)!},$$
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$$\cos(z)= \displaystyle\sum_{k=0}^{\infty} \dfrac{(-1)^k (z-z_0)^{2k}}{(2k)!},$$
 
where $\cos$ denotes the [[cosine]] function.
 
where $\cos$ denotes the [[cosine]] function.
 
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Revision as of 06:23, 25 March 2016

Theorem: Let $z_0 \in \mathbb{C}$. The following Taylor series holds: $$\cos(z)= \displaystyle\sum_{k=0}^{\infty} \dfrac{(-1)^k (z-z_0)^{2k}}{(2k)!},$$ where $\cos$ denotes the cosine function.

Proof: