Why is great circle the shortest distance?

Related questions

1. Is the Concorde still flying?
2. Why are eastbound flights faster?
3. Why can't planes fly into space?
4. Do pilots adjust for curvature?
5. What determines flight paths?
6. Why don't we fly east to go from India to USA?
7. Do any flights go over Antarctica?
8. Do planes fly over Tibet?
9. Why do planes not fly directly over the Pacific Ocean?
10. How does the great circle route work?

Tags

1. #sphere
2. #length
3. #points
4. #between
5. #distance
6. #through
7. #circle
8. #orthodromic
9. #measured
10. #great
11. #shortest
12. #shorter
13. #surface
14. #along
15. #opposed
16. #interior
17. #straight