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Eventually she leads us toward more abstract concepts such as the polar coordinate system, a graphical approach to defining a point using distance and angle, as well as irrational numbers and decimals that repeat infinitely.

And whereas Ptolemy based his coordinate system on the ecliptic, Hipparchus used the celestial equator, a system more common in modern star maps.

Invent a coordinate system where the ship’s bow—the single most important reference point in this Seussian landscape—serves as the axis around which everything else is oriented.

At the very center of the coordinate system—where the two axes cross—sits a zero.

Most states mandate the use of the old U.S. survey foot for their state coordinate systems, which allow surveyors to take into account Earth’s curvature in their measurements.