Before revision: The relevant formulas (derived using the spherical trigonometric identities) are: ] with the same is not unique (since ), but is defined only in .
After revision: The adjustment from Z to Zn (which is in , and measured from North) has two reasons:(1)The angles in0,360The relevant formulas (derived using the spherical trigonometric identities) are: ] with the same is not unique (since ), but is defined only in .