calculate to the nearest mile the distance between

P(26 degrees north,70 degrees west), Q(72 degrees S, 70 degrees W)

and

R(o degrees,50 degrees East), S(o degrees, 32 East) along the equator.

and

A ship leavers rio at midday and sails south at a steady 15 knots.

What are the co-ordinates od the ship at 2000 hours.

If it continues on the same bearing at the same speed what time should it reach its co-ordinates (28degrees south, 43 degrees West)

discuss your solutions the mathematical models that enable these calculations to be made and the crediibilty you can give their accuracy.

thanks.