Question #59822

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Answer 1 · 2017-10-11T21:51:07

For $- π \leq x \leq π$ $-pi <= x <= pi$ :

$x = - 2.35619449, 2.35619449$ $x = -2.35619449, 2.35619449$

$2 cos (\frac{x}{3}) - \sqrt{2} = 0$ $2cos(x/3) - sqrt(2) = 0$

$2 cos (\frac{x}{3}) = \sqrt{2}$ $2cos(x/3) = sqrt(2)$

$cos (\frac{x}{3}) = \frac{\sqrt{2}}{2}$ $cos(x/3) = sqrt(2)/2$

$\frac{x}{3} = {cos}^{- 1} (\frac{\sqrt{2}}{2})$ $x/3 = cos^-1(sqrt(2)/2)$

$x = 3 \cdot {cos}^{- 1} (\frac{\sqrt{2}}{2})$ $x = 3 * cos^-1(sqrt(2)/2)$

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

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