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

Watch
Announcements
#1
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.
0
10 months ago
#2
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.
0
10 months ago
#3
(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.
0
#4
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.
Last edited by Ardipithecus; 10 months ago
0
10 months ago
#5
(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
0
10 months ago
#6
(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).
0
#7
(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!
1
#8
(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!
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Should there be a new university admissions system that ditches predicted grades?

No, I think predicted grades should still be used to make offers (501)
33.58%
Yes, I like the idea of applying to uni after I received my grades (PQA) (620)
41.55%
Yes, I like the idea of receiving offers only after I receive my grades (PQO) (303)
20.31%
I think there is a better option than the ones suggested (let us know in the thread!) (68)
4.56%