I think an answer in the A-level edexcel textbook may be wrong

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Ardipithecus
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I've been doing the questions from the 'Modelling with vectors' chapter (11.6) and the answer given does not seem to make any sense. It's question 8)b):
A boat has a position vector of (2i+j)km and a buoy has a position vector of (6i-4j)km. Find the bearing of the boat from the buoy.
Just keen to see what answer anyone else has gotten, because its been really bugging me, and it you could explain to me how you get it, that would be great. I feel like the answer that they give in the textbook (303.7 degrees) would be the bearing of O (the origin) from the buoy, which is why I don't understand.
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PetitePanda
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Yeah that happened with my aqa physics textbook which my teacher told me i was right it was wrong. Just tell your teacher it doesn’t make sense and they’ll tell you if it was wrong or the reason why it was written that way.
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mqb2766
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(Original post by PigeonParliament)
I've been doing the questions from the 'Modelling with vectors' chapter (11.6) and the answer given does not seem to make any sense. It's question 8)b):
A boat has a position vector of (2i+j)km and a buoy has a position vector of (6i-4j)km. Find the bearing of the boat from the buoy.
Just keen to see what answer anyone else has gotten, because its been really bugging me, and it you could explain to me how you get it, that would be great. I feel like the answer that they give in the textbook (303.7 degrees) would be the bearing of O (the origin) from the buoy, which is why I don't understand.
What did you get? Upload your working pls.
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Ardipithecus
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This is my working out. I'm not the best at maths tbh, so I've probably made some mistake along the way, but I'd really love to learn the right method! My answer is 321.4 degrees, in case its not visible at the bottom.
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mqb2766
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(Original post by PigeonParliament)
This is my working out. I'm not the best at maths tbh, so I've probably made some mistake along the way, but I'd really love to learn the right method! My answer is 321.4 degrees, in case its not visible at the bottom.
I got 321 as well. Your working seems ok, but could be simpler.
* Boat - buoy = (-4i + 5j)km
* atan (5/4) = 51 degrees
* orientation = 51 + 270 = 321
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MarkFromWales
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(Original post by PigeonParliament)
This is my working out. I'm not the best at maths tbh, so I've probably made some mistake along the way, but I'd really love to learn the right method! My answer is 321.4 degrees, in case its not visible at the bottom.
Yes, I agree with your answer and also that 303.7° is the bearing of O from the buoy.

P.S. you can get the answer more easily if you just find the vector from the buoy to the boat (-4i + 5j).
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Ardipithecus
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(Original post by mqb2766)
I got 321 as well. Your working seems ok, but could be simpler.
* Boat - buoy = (-4i + 5j)km
* atan (5/4) = 51 degrees
* orientation = 51 + 270 = 321
thanks so much for your help! this is the first time i've used the student room and I can't believe how quick and effective it is!
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Ardipithecus
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(Original post by MarkFromWales)
Yes, I agree with your answer and also that 303.7° is the bearing of O from the buoy.

P.S. you can get the answer more easily if you just find the vector from the buoy to the boat (-4i + 5j).
Thanks so much, I see that now!
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