...the axis of ©ABC. 6. P is a pole of ©ABC. pendicular to the plane of the lines. 5. The axis of a circle of a sphere is the diameter of the sphere which is perpendicular to the plane of the circle. 6. The extremities of the axis are the poles of the circle. • PROBLEM 822 Given two polar triangles,...

...Figure 2.14 great circle Definition 2 The axis of any circle (small or great) of a sphere is the unique diameter of the sphere which is perpendicular to the plane of the circle. The extremities of such a diameter are called the poles of the circle. See Figure 2.15. Definition 3 The...

...circles on the spherical surface are like straight lines on a plane surface. The axis of any great circle is the diameter of the sphere, which is perpendicular to the plane of the great circle; the extremities of the axis are called the poles of the great circle. The length...