Chapter 10 - Parametric Equations and Polar Coordinates - 10.3 Exercises - Page 687: 15

This curve represents a circle with radius equal to $\sqrt 5$ and center at $(0,0)$.

- Knowing that $r^2 = x^2 + y^2$ $r^2 = 5$ $x^2 + y ^2 = 5$ - This Cartesian equation follows the pattern* for a circle with its center at the origin (0,0), and the radius is equal to $\sqrt {(radius)^2} = \sqrt 5$. * Pattern: $x^2 + y^2 = (radius)^2$