What is a great circle?

A great circle is an essential concept in navigation and geometry. It is defined as the largest circle that can be drawn on a sphere, which means it divides the sphere into two equal hemispheres. This property allows a great circle to serve not only as a boundary but also as a line representing the shortest distance between two points situated on the surface of that sphere.

In practical navigation terms, when planning the most efficient route for aircraft or ships, navigators utilize great circles. By following this path, they minimize travel distance, which can save time and fuel.

Therefore, acknowledging both its definition as the largest circle that can be drawn on a sphere and its function as the shortest path between two points confirms that both aspects are encompassed in the correct answer. This dual recognition is what makes the concept of the great circle fundamentally important in navigation practices.