$[1\mathrm{.}34/2$ Points$]$

Let $g(x,y)=cos(x2y).$

$($a$)$ Evaluate $(2,-1).$

$(2,-1)=x$

$($b$)$ Find the domain of $g.$

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$-\frac{}{2}x2y\frac{}{2}$

$-1x1,-\frac{1}{2}y\frac{1}{2}$

$$

$-2x2,-1y1$

$$

$-1x2y1$

$R^2$

$($c$)$ Find the range of $g.($Enter your answer using interval notation.$)$

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