Difference between revisions of "Cosine"
From specialfunctionswiki
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Revision as of 05:09, 19 October 2014
The cosine function, $\cos \colon \mathbb{R} \rightarrow \mathbb{R}$ is the unique solution of the second order initial value problem $$y=-y;y(0)=1,y'(0)=0.$$
