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Mathematics 19 Online
OpenStudy (anonymous):

A ship leaves port at 1:00 P.M. and sails in the direction S35°E at a rate of 24 mi/hr. Another ship leaves port at 1:30 P.M. and sails in the direction S20°W at a rate of 18 mi/hr. Approx. how far apart are the ships at 3:00pm I made a picture and I dont know if I need to add some to the side to correspond with the changing times

OpenStudy (perl):

What is the question asking , i think you left that out in the directions.

OpenStudy (anonymous):

Oh sorry. Approx. how far apart are the ships at 3:00pm

OpenStudy (perl):

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OpenStudy (perl):

I drew the south line just to aid us. So we want to know how far apart are the two vectors

OpenStudy (perl):

first lets find the magnitude of each vector. Distance = rate * time

OpenStudy (perl):

A ship leaves port at 1:00 P.M. and sails in the direction S35°E at a rate of 24 mi/hr. Another ship leaves port at 1:30 P.M. and sails in the direction S20°W at a rate of 18 mi/hr. Approx. how far apart are the ships at 3:00pm the first vector distance = 24 mi/hr * 2 hr = 48 mi second vector distance = 18 mi/hr * 1.5 hr = 27 mi

OpenStudy (perl):

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OpenStudy (perl):

now we can use law of cosines for that triangle

OpenStudy (perl):

Law of cosines : a^2 + b^2 - 2*a*b*cos(C) = c^2 27^2 + 48^2 - 2*27*48*cos(20 + 35 degrees) = x^2

OpenStudy (perl):

then take the square root of the both sides x = √ [27^2 + 48^2 - 2*27*48*cos(55 degrees)]

OpenStudy (anonymous):

(24)(2) For the first vector, It wouldn't be something different because we started at 1:30 and we're going to 3?

OpenStudy (anonymous):

That would be why perl only put "1.5 hr"

OpenStudy (anonymous):

I get that for the second vector yes but the first one is at a different time

OpenStudy (perl):

|dw:1432576933066:dw|

OpenStudy (perl):

the first vector (boat) travels from 1 pm to 3 pm, so 2 hours. the second vector (boat) travels from 1:30 pm to 3 pm, so 1.5 hours

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