Chapter 10 - Conics, Parametric Equations, and Polar Coordinates - Review Exercises - Page 744: 78

$$y = - x$$

$$\eqalign{ & \theta = \frac{{3\pi }}{4} \cr & \tan \theta = \tan \left( {\frac{{3\pi }}{4}} \right) \cr & \frac{{\sin \theta }}{{\cos \theta }} = - 1 \cr & {\text{Convert to rectangular form, using }}y = r\sin \theta ,{\text{ }}x = r\cos \theta \cr & \frac{{y/r}}{{x/r}} = - 1 \cr & \frac{y}{x} = - 1 \cr & y = - x \cr & {\text{Graph}} \cr} $$