



 
"Assuming that the earth is a sphere of radius 6378 kilometers,..." Don't! Instead, assume, as the committee defining the metre did, that it is an approximate sphere of quartercircumference (measured NS) 10,000 km. 10000 km = 90 degrees So you can work out how many degrees are in 100 km and 400 km, can't you? Good Hunting!  


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