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How many ordered pairs of $(x, y$) exist in the following case?

$$\cos(x+y) = 1/e$$

$$\cos(x-y) =1$$

where both $x, y$ are less than or equal to pi.

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    You probably also want to give a lower bound on $x$ and $y$ (or alternatively, give a bound on their absolute value).2012-08-08

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