Distance Question

http://www.movable-type.co.uk/scripts/latlong.html

I haven't worked it out yet but this site may help you.

It works it out in km which seems a bit odd but you can do the conversion.
1 nautical mile (nm) = 1.85200 kilometer (km).

Maybe you already know that 1 degree of arc from the centre of the Earth is equal to 1 nm at the equator.

There might be a much better way of working it out. I really don't know.

You can ignore this stuff, I have answered again below.

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What is the number of nautical miles between place A (15°N, 90°W) and place B (40°S, 90°E)?
The answer should consist relative to [ 9600 n mi]

I was thinking......
These 2 places are on a great circle of the earth. (90degreesW and 90degreesE are 180degrees apart.)
This means that the shortest distance between them is via the north or south pole.
40degrees South is further from the equator than 15degrees north so i am going to go via the south pole.
The south pole is 90degrees south

40degrees to 90degrees is 50degrees so B is 50degrees worth of distance from the south p ole
Going up the other side now.
The south pole to the equator is 90degrees.
The equator to A is 15degrees

50+90+15 = 155 degrees. (This is less than half of 360 degrees so it must be the shortest way)
Now 1 degree at the centre of the earth is 60nm at the equator (which is another great circle)
so
155 degrees * 60 = 9300nm

I worked on it and came out with the same answer of 9300nm.
Thanks