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Penetrating so many secrets, we cease to believe in the unknowable. But there it sits nevertheless, calmly licking its chops.
-- H. L. Mencken

$$\cos x = \sum\limits_{n = 0}^\infty {\frac{{\left( { - 1} \right)^n x^{2n} }}{{\left( {2n} \right)!}}}$$