I have the longitude and latitude of a known point O(x,y) where x and y are obtained from transforming the longitude and latitude from EPSG 4326 to EPSG 32635. This is the observer point. I have another point A(x1, y1) whose coordinates I don't know, but I know the distance from O to A in meters and the azimuth from O to A in radians.
How can I compute the coordinates of A knowing only these?
A function in Qgis in C++ would be the most useful, or at least a mathematical formula would be great.