# How do you write this equation in polar coordinates: x^2 + y^2 = 2?

$\left\{\left(r , \theta\right) : {r}^{2} = 2\right\}$
${x}^{2} + {y}^{2} = 2$ is a circle with radius ($r$) equal to $2$
Note that the angle ($\theta$) is not constrained by this equation (similar to the way $y$ is not constrained by the linear equation $x = 5$)