What is grivation?

The angle between magnetic north and grid north

What are chart lines that join points of equal grivation called?

Isogrivs

What is the equation for calculating the highest latitude reached by a G.C?

Original lat + x

x = (CA + total R.L distance)/230

(in nm)

What are G.C vertices?

The points of a G.C that reach the highest latitudes and are antipodal.

How do the longitude and latitude of each G.C vertex compare to each other?

N/S lat are the same value just in opposite hemispheres

E/W longitude values sum to 180deg

When considering G.C vertices, when is the equator crossed?

At the mid point (90deg) between the vertices.

What can be said about the track at the equator when a G.C crosses it and the vertices are known?

The track, from south to north, is equal to the latitude of the vertices.