Final answer:
An airplane pilot can end up anywhere on the circle shown in Figure 3.48 because they're following the arc of a great circle. To get to Sacramento, the pilot would need additional information regarding the direction, altitude, and speed.
Step-by-step explanation:
An airplane pilot can end up anywhere on the circle shown in Figure 3.48 because the shortest distance between two points on a sphere is along the arc of a great circle.
The Earth is approximately spherical in shape, so when the pilot flies in a straight line from San Francisco to Sacramento, they are actually following along a segment of a great circle. In this case, the circle represents all the possible flight paths that are 123 km long and connect San Francisco and Sacramento.
In order to get to Sacramento, the pilot would need additional information such as the direction or bearing they should follow along the great circle and any necessary altitude or speed adjustments. This information can be provided through navigational aids, charts, and communication with air traffic control.