Take a bearing on it from a known location.
Move a known distance and take another bearing.
Make it far enough to give substantially different bearings, say a 30° to 45° difference.
Two angles and one side make it a standard trig calculation to find the distance to it.
Knowing the coordinates of the locations where the bearings were taken makes it an easy task to convert the distances to a coordinate.
Formulas and/or methods should be easy to find in a Google search.