Given that the cardioid has a characteristic heart-like shape, it is enough to know its orientation, its intercepts, and that it passes through the origin. The two $y$-intercepts occur at $\mathrm{\θ}\=\mathrm{\π}\/2$ and $\mathrm{\θ}\=3 \mathrm{\π}\/2$; the $x$-intercept, at $\mathrm{\θ}\=\mathrm{\π}$. Consequently, $r\left(\mathrm{\π}\/2\right)\=2$, $r\left(\mathrm{\π}\right)\=4$, and $r\left(3 \mathrm{\π}\/2\right)\=2$. This would be enough data for sketching a graph of the cardioid. Figure 7.1.5(a) is a Maple-drawn graph of the cardioid, graphed as a polar curve.

Alternatively, convert to Cartesian coordinates, obtaining

Alternatively, use the .

In the first pane of the Interactive Plot Builder, make the selections shown in the upper portion of Figure 7.1.5(b). The Interactive Plot Builder defaults to an implicit plot.

Change the ranges for $r$ and $\mathrm{\θ}$ to those shown in Figure 7.1.5(b).

Then, click on the Options button, and in the lower-left corner change the coordinate system to the option shown in the lower portion of Figure 7.1.5(b).

The resulting graph will be Figure 7.1.5(a).