A heart-shaped graph, or a cardioid, is represented using parametric or polar functions, rather than a standard y-dependent-on-x cartesian equation.
A heart-shaped graph is typically an example of a parametric function or a polar function. These types of functions are used to describe curves that are not easily expressed with a regular cartesian coordinate system where a variable y is directly dependent on a variable x.
In the case of the heart-shaped graph, which is also known as a cardioid, we use parametric equations involving both sin and cos functions or polar coordinates to plot the points on the graph that form the shape of a heart.
The probable question may be: "a heart shaped graph is that an example of which function?"