The shortest trade route between India and Constantinople would be the land and sea route. This route would involve traveling overland from India to a port on the Arabian Sea, then sailing across the Arabian Sea, through the Red Sea, and finally into the Mediterranean Sea to reach Constantinople. This combination of land and sea travel would be more efficient than either the land or sea route alone due to geographical constraints and historical trade patterns.
constantinople
A straight line
the shortest air route is a great circle
since air travel can fly a more direct route, not having to circumnavigate land mass, it would be the shortest distance.
chennai to tehran, paris and london
who am I
The shortest route between two points on the surface of a planet, when routes are limited to the planet's surface, is the arc of the great circle that connects the two points. The shortest route between two points anywhere, without regard to intervening matter or energy preventing the route from being followed, is always the line connecting the two points.
Great Circle Route
It was the Suez Canal, which was a short cut between the Mediterranean Sea and the Indian Ocean, leading to India, Australia and Asia.
The fastest shortest path algorithm for finding the most efficient route between two points is Dijkstra's algorithm.
straight line