vectors!!! help me refresh

- anonymous

vectors!!! help me refresh

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- zzr0ck3r

so think if we are at the point (0,0) and we use vector d=(1,2) to get to our new position
|dw:1377848834415:dw|
well what will e=-d=(-1,-2) do?

- anonymous

|dw:1377848964298:dw|
it will be the reverse process, right

- zzr0ck3r

yeah

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## More answers

- anonymous

so what i can't recall is how to solve this problem...i guess e = -d = -24 meters is answer but not sure

- zzr0ck3r

well if we are considering R^2 ( 2 dimensions ) then tipically we would call in the x direction "east" so our vector d will be d = (24,0) and -d=(-24,0)

- zzr0ck3r

these are vectors not real numbers.

- anonymous

oh ya...i gotcha...its the graph...ok now help me totally understand it...lets say now |dw:1377849289057:dw|
so the answer would be e = 3d = (72,0) ???

- zzr0ck3r

you can think of (0,24) is the vector you are adding on to where you are
different example
|dw:1377849291035:dw|
|dw:1377849369564:dw|

- zzr0ck3r

correct

- anonymous

where did p come from

- zzr0ck3r

that is just some random point ( where we started )

- zzr0ck3r

|dw:1377849511465:dw|

- zzr0ck3r

so we add head to tale

- anonymous

yea correct...head to tail but i can't see P in my question....just D

- zzr0ck3r

if we add -d we will be back at the start|dw:1377849583801:dw|

- zzr0ck3r

well we are given instructions to move to some place, that means we are in some place right now. Call that P. I just choose a random point/vector to call P

- anonymous

alright. So we are at position P right now....we started from p to 24 m east i.e. d...if we got e = -d we would be back to where we started. So what are the instructions??? or what does it mean

- zzr0ck3r

I guess you would call them reverse instructions. I dont know what they want for an answer. I dont know if they want the vector or what the vector does. just write down both

- zzr0ck3r

I actually would just say that it gives reverse directions

- zzr0ck3r

we are assuming allot by placing our graph where x means east.... it could be 3d it could be 4d...... but in all cases it will be revirse directions

- anonymous

alright so e=2d gives twice the original direction, 3d gives thrice, -2d gives 2 times reverse direction etc right

- zzr0ck3r

correct, essentially what this wants you to understand, is that if we have a vector d, then -d just flips it|dw:1377850279820:dw|

- zzr0ck3r

my point with these drawings is that vectors have no placement, they are the same if we move them around....
but in your situation we are using the vector as a direction from where we are, so we start there

- zzr0ck3r

and everything there should be parallel....

- anonymous

gotcha...one last question lets say that there is now vector H which represents "go to 24 m south of where you are now" and D is the same. How can we represent Get to 34 m SOUTHEAST and to position 34 m SOUTHWEST of where you are now

- anonymous

|dw:1377850603155:dw|

- zzr0ck3r

correct
and
\[\sqrt{24^2+24^2}\approx34\]|dw:1377850795358:dw|

- zzr0ck3r

I think that was the point with the 34

- zzr0ck3r

wait that is se and ne
we want sw
what will that be?

- anonymous

oh wait it is southwest not northeast

- anonymous

-d +h

- zzr0ck3r

correct

- anonymous

awesome man...totally understood the first part but still can't figure out instructions

- zzr0ck3r

addition is commutative with vectors so we can write h-d

- zzr0ck3r

yeah, I think it just wants you too say reverse directions, or inver instructions

- zzr0ck3r

exactly how was it worded?

- anonymous

suppose vectors d and h are defined AS I SAID. how can you represent instructions "get to position about 34 meters southwest of where you are now"

- zzr0ck3r

ok the vector "represents" instructions
so the vector IS instructions
they tell you to "write instructions"
that means write a vector
that vector is -d

- zzr0ck3r

ok reading it like that
d = (24,0)
-d = (-24,0)
se = d+h
sw = h-d

- zzr0ck3r

d+h = (24,0)+(0,-24))=(24,-24)
magnitude(the length) of (24,-24) is about 34

- anonymous

yeah and wording wise it will be se = go to east and then south and sw would be go to h and opposite direction of d...

- zzr0ck3r

rvb

- zzr0ck3r

brb

- anonymous

kk

- anonymous

I will just close this question. I think I got it

- zzr0ck3r

aight

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