Q:If $\displaystyle x$ and $\displaystyle y$ satisfy the equations

$\displaystyle \mathrm{cosh}x \mathrm{cosh}y = 2$

$\displaystyle \mathrm{sinh}x \mathrm{sinh}y = -1$

Show that $\displaystyle x = -y = \pm \ln (1 + \sqrt{2})$

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My Problem:I did this question by changing the hyperbolic function in terms of $\displaystyle e$ but did not get the correct answer. Can someone do this question and show me how they obtained the correct answer? Thanks in advance.