# Which is orientation of tangential angle in polar coordinates?

## Main Question or Discussion Point

In the wiki, there is an explanation for what is the tangential angle in cartesian and polar coordinates. However, the orientation these angles aren't specified. In cartesian coordinates, I believe that the tangential angle φ is measured from the x-axis, in polar coordinates the tangential angle ψ is measured from radial axis?

https://en.wikipedia.org/wiki/Subtangent
https://en.wikipedia.org/wiki/Tangential_angle

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Chestermiller
Mentor
In the wiki, there is an explanation for what is the tangential angle in cartesian and polar coordinates. However, the orientation these angles aren't specified. In cartesian coordinates, I believe that the tangential angle φ is measured from the x-axis, in polar coordinates the tangential angle ψ is measured from radial axis?

https://en.wikipedia.org/wiki/Subtangent
https://en.wikipedia.org/wiki/Tangential_angle
From your reference, it looks like, in polar coordinates, ψ is the angle that the tangent to the curve makes with a unit vector in the radial direction at the specified point.