The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

M1 Vectors Help!!

Need help on this



Diagram



worked out theta to be 78.3 degrees, so the bearing should be 360 - 2x78.3 but its wrong?


HELP!
help.PNG10.3KB
M1C606.jpg10.1KB
Original post by bluegirl32
Need help on this



Diagram



worked out theta to be 78.3 degrees, so the bearing should be 360 - 2x78.3 but its wrong?


HELP!


Diagram not drawn accurately

I get theta = 78.58

But B to c1 isn't North. If it was North it'd have to be 110.
(edited 9 years ago)
Reply 2
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
I get theta = 78.58


Oh sorry - yes I did get that.

I don't know how to deduce the direction :/
Original post by bluegirl32
Oh sorry - yes I did get that.

I don't know how to deduce the direction :/


Just edited my response so perhaps that will help.
Reply 4
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
Just edited my response so perhaps that will help.



Still dont get it :lol:
Original post by bluegirl32
Still dont get it :lol:



OK. The diagram looks as if C1 is North of B. You've calculated that the angle theta is acute but the diagram is showing an obtuse angel (hence diagram not drawn accurately.

If you drew in a North from B then theta would have to be 110 (interior angles of parallel lines). Now you can see that C1 is actually 31.42 degrees anticlockwise from North.

Is one of the answers 328.58? If so my explanation seems to work out. If not ignore what I've said and I'll rethink.

Let me know.
Reply 6
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
OK. The diagram looks as if C1 is North of B. You've calculated that the angle theta is acute but the diagram is showing an obtuse angel (hence diagram not drawn accurately.

If you drew in a North from B then theta would have to be 110 (interior angles of parallel lines). Now you can see that C1 is actually 31.42 degrees anticlockwise from North.

Is one of the answers 328.58? If so my explanation seems to work out. If not ignore what I've said and I'll rethink.

Let me know.


Yes one of the answers is 328 :smile:

ah i understand what you're saying but diagramatically I cant really think it, like why is it anticlockwise btw?

this is my diagram now

m1.png19.9KB
Original post by bluegirl32
Still dont get it :lol:



Does this diagram help at all?
Scan0008.pdf287.0KB
Reply 8
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
Does this diagram help at all?


YES :biggrin:

so how did you end up with 328 :smile:
Original post by bluegirl32
YES :biggrin:

so how did you end up with 328 :smile:



You know the 78. 58 and the 110 so you can calculate that little angle between C and North.

Bearings are always taken from North in a clockwise direction so you have to take that little angle off 360.

OK? or NOT OK?
(edited 9 years ago)
Reply 10
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
You know the 78. 58 and the 110 so you can calculate that little angle between C and North.

Bearings are always taken from North in a clockwise direction so you have to take that little angle off 360.

OK? or NOT OK?


Ah, I'm still confused on how to get the bearings!

I understand everything else though!
Original post by bluegirl32
Ah, I'm still confused on how to get the bearings!

I understand everything else though!



You stand at B with your arm pointing North. Then you twiz round until your arm is pointing at C. And how many degrees you have twizzed through is the bearing.

Here is an updated diagram.

What do you think now?
Scan0009.pdf329.5KB
Reply 12
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
You stand at B with your arm pointing North. Then you twiz round until your arm is pointing at C. And how many degrees you have twizzed through is the bearing.

Here is an updated diagram.

What do you think now?


Oh yes I get it now! thanks!!!!

now for the other solution?
Original post by bluegirl32
Oh yes I get it now! thanks!!!!

now for the other solution?



Oh, I bet you can do that.

Just draw on the other position and the solution will just jump out at you.
Reply 14
Avatar for bluegirl32
bluegirl32
OP

Original post by maggiehodgson
Oh, I bet you can do that.

Just draw on the other position and the solution will just jump out at you.


the answer is not right though :frown:
m12.jpg125.3KB
Original post by bluegirl32



the answer is not right though :frown:



Well, that's not what I had an idea about. You know how far you have to twizz for C1. But look where C2 is. It's before C1 and you know how many degrees before C1.

Doing it your way, you have assumed that the A, C1, C2 diagram is evenly spread and have thought that the angle between C2 and South is the same as between C1 and North.

If I don't reply tonight I will tomorrow. My friends have just arrived.
Reply 16
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
Well, that's not what I had an idea about. You know how far you have to twizz for C1. But look where C2 is. It's before C1 and you know how many degrees before C1.

Doing it your way, you have assumed that the A, C1, C2 diagram is evenly spread and have thought that the angle between C2 and South is the same as between C1 and North.

If I don't reply tonight I will tomorrow. My friends have just arrived.


I think I got the right answer

360 - (78.58 + 110) = 171.42
Reply 17
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
Well, that's not what I had an idea about. You know how far you have to twizz for C1. But look where C2 is. It's before C1 and you know how many degrees before C1.

Doing it your way, you have assumed that the A, C1, C2 diagram is evenly spread and have thought that the angle between C2 and South is the same as between C1 and North.

If I don't reply tonight I will tomorrow. My friends have just arrived.


Angle of C2 = 78.58,

Angle of C1 to north = 110,

Is this right?

Thank you so much for all your help!
Original post by bluegirl32
I think I got the right answer

360 - (78.58 + 110) = 171.42


'Twas a false alarm. Friends not here yet.

I'm so pleased that you've sussed it. I can go out this evening without thinking that you are frustrated with the question.
Reply 19
Avatar for bluegirl32
bluegirl32
OP
Original post by maggiehodgson
'Twas a false alarm. Friends not here yet.

I'm so pleased that you've sussed it. I can go out this evening without thinking that you are frustrated with the question.

hahahahahaha thank you x :biggrin:

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you