I have a Great Circle on Earth, which is not an Equator nor Meridian, and it's not parallel to these. I have four geographical coordinate pairs for it, separated by 90 degrees, so I can use these in KML files and display the circle in Google Earth.
From these coordinates I need to calculate the Longitude and Latitude pairs for a Small Circle that is parallel to that Great Circle and x degrees away from it.
I know how to draw small circles parallel to Equator, which means just adding some degrees of latitude to Equator (or subtracting), but how you do it when you have a Great Circle that is not an Equator or Meridian?
Can it be done like Equatorial coordinates conversion into Ecliptical coordinates in Astronomy?
I have been trying to use this formula but with no success.