The geomagnetic poles are antipodal points where the axis of a theoretical dipole intersects the Earth's surface.
Trail, or caster, is the horizontal distance from where the steering axis intersects the ground to where the front wheel touches the ground.
The South Pole is the other point where the Earth's axis of rotation intersects its surface, in Antarctica.
Polar motion of the Earth is the movement of the point where Earth's rotational axis intersects its surface.
But when displaced from the origin by η, this axis intersects every sheet.
The primary reference points are the poles where the axis of rotation of the Earth intersects the reference surface.
The origin of the complex plane can be referred as the point where real axis and imaginary axis intersect each other.
Similarly the centre of an ellipse is where the axes intersect.
In fact, it would require precision to make the ring laser's axis intersect Earth's rotational axis.
Consider point G at which the radical axis intersects one of the two given lines.
