postgis - How to get the rotation of a square Polygon?

I've got a layer made of perfect square polygons. I would like to obtain the rotation of each polygon:

In this case, the rotation would be 45 degrees.

I suppose I would have to compare it with a 0 rotation polygon, which has all of its sides parallel to the X axis or the Y axis. Example:

Answer

I agree with @user30184... and here is the code:

WITH poly AS (SELECT ST_MakePolygon(ST_GeomFromText('LINESTRING(75.15 29.53,77 29,77.6 29.5, 75.15 29.53)')) as geom)

SELECT degrees(ST_Azimuth(ST_PointN(ST_ExteriorRing(geom),1),ST_PointN(ST_ExteriorRing(geom),3))) as degAz
FROM poly;

I would also add the obvious, that this solution would work decently for a somewhat square or rectangular polygon as in the example but not for more complex polygons.

In that case, perhaps this code could be used for more complex polygons which gets the azimuth from the first point to the center of the polygon:

WITH poly AS (SELECT ST_MakePolygon(ST_GeomFromText('LINESTRING(75.15 29.53,77 29,77.6 29.5, 75.15 29.53)')) as geom)


SELECT degrees(ST_Azimuth(st_centroid(geom),ST_PointN(ST_ExteriorRing(geom),1))) as degAz
FROM poly;