Definition:Cartesian Coordinate System/Y Coordinate

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Definition

Consider a Cartesian coordinate system $C$ with a $y$-axis.

Let a point $Q$ be positioned in $C$.


Let $y$ be the length of the line segment from the origin $O$ to the foot of the perpendicular from $Q$ to the $y$-axis.

Then $y$ is known as the $y$ coordinate.

If $Q$ is in the positive direction along the real number line that is the $y$-axis, then $y$ is positive.

If $Q$ is in the negative direction along the real number line that is the $y$-axis, then $y$ is negative.


Also known as

An archaic term for the $y$ coordinate which is sometimes seen is ordinate.


Also see


Sources