# Which is orientation of tangential angle in polar coordinates?

1. Feb 27, 2014

### Jhenrique

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

2. Feb 27, 2014

### Staff: Mentor

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.