Question #59822

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Answer 1 · 2017-10-11T21:51:07

For $-pi <= x <= pi$ :

$x = -2.35619449, 2.35619449$

$2cos(x/3) - sqrt(2) = 0$

$2cos(x/3) = sqrt(2)$

$cos(x/3) = sqrt(2)/2$

$x/3 = cos^-1(sqrt(2)/2)$

$x = 3 * cos^-1(sqrt(2)/2)$

The graph below represents $y = 2cos(x/3)$ and $y = sqrt(2)$

![www.desmos.com](useruploads.socratic.org)