Two theodolite method for setting out a circular curve is based on the principle that
1
The angle between the tangent and the chord is equal to the angle subtended by the chord in the same segment.
2
The angle between the tangent and the chord is equal to the angle subtended by the chord in the opposite segment.
3
The angle between the tangent and the chord is equal to half the angle subtended by the chord in the same segment.
4
The angle between the tangent and the chord is equal to half the angle subtended by the chord in the opposite segment.