Why angleAtVertex() returns different value than angle_at_vertex in Field Calculator using PyQGIS

Question

When using

angle_at_vertex($geometry,0)
324.022

in the Field Calculator of QGIS the values seem correct from a visual check. However when using

feature.geometry().angleAtVertex(0)
5.616644978134382

in PyQGIS it returns a different value that doesn't appear to be right.

So far I made sure that the layer's CRS and the project's CRS are the same but I am still getting the same different values. What am I missing out on?

Answer 1

angle_at_vertex() returns the angle in degrees:

anlge_at_vertex($geometry, 0) -> 38.618825502347555 degree

angleAtVertex() returns the angle in radians:

feature.geometry().angleAtVertex(0) -> 0.674025658269118 radian

For example

38.618825502347555 * pi / 180 = 0.674025658269118