Instead of Cartesian coordinates, we use cylindrical coordinates for situations you will see in future sections.
For now, we will just learn how to convert from 3D Cartesians coordinates to 3D cylindrical coordinates, and vice versa. In other words,
Suppose we have the following graph:
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Since the z coordinate doesn't change from converting, we will just focus on the x and y. Thus, we make it into 2D graph:

From this graph, we can get the following equations: