Parallel sailing

                  A ship leaves a positions in lat 49°00’ N longitude 160°00’ W and steams 000°(T) for 20 miles, 090°(T) for 20 miles, 180°(T) for 20 miles and 270°(T) for 20 miles.What is her final position?

                   000°(T) for 20 miles

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Initial latitude     49°00’N

d’lat                    0°20’N

Latitude             49°20’N                      

090°(T) for 20 miles

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cos lat = dep / d’long

d’long = dep / cos lat

d’long = 20 / cos 49°20’

d’long =30.69’ E

d’long = 0°30.7’E                                

Initial long     160°00’W

d’long           0°30.7’E

Longitude     159°29.3’W                      

180°(T) for 20 miles

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Lat              49°20’ N

d’lat              0°20’ S

Final lat       49°00’ N                          

270°(T) for 20 miles

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cos lat = dep / d’long

d’long = dep / cos lat

d’long = 20 / cos 49°

d’long = 30.485’ W

d’long = 0°30.5’ W                             

Long          159°29.3’W

d’long           0°30.5’ W

Final long   159°59.8’ W 

Position      49°00’ N      159°59.8’ W