Vector problems

Jul 2010
7
0
I just started on vector and there are some confusing problems i want to ask:

Find the magnitude and direction angle of the vector:
1)\(\displaystyle 3i-4j\)<- on this one i found the magnitude but not the direction angle, though i'm positive that i did just like i've done with some previous problems. I got 53.13, but the answer in the book is 306.87

2)\(\displaystyle -3i-5j\)<-- i also got the magnitude of this one, but not the direction angle. again :(

3)\(\displaystyle 7(cos135i+sin135j)\)

Find the vector v with the given magnitude and the same direction as u
\(\displaystyle |v| = 1, u =<3,-3>\)
Please help! Thanks(Happy)
 
Last edited:

skeeter

MHF Helper
Jun 2008
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I just started on vector and there are some confusing problems i want to ask:

Find the magnitude and direction angle of the vector:
1)\(\displaystyle 3i-4j\)<- on this one i found the magnitude but not the direction angle, though i'm positive that i did just like i've done with some previous problems. I got 53.13, but the answer in the book is 306.87

+i , -j ... quadrant IV angle

2)\(\displaystyle -3i-5j\)<-- i also got the magnitude of this one, but not the direction angle. again :(

-i , -j ... quadrant III angle

3)\(\displaystyle 7(cos135i+sin135j)\)

what is your problem with this vector?

Find the vector v with the given magnitude and the same direction as u
\(\displaystyle |v| = 1, u =<3,-3>\)

v = < 1/sqrt(2) , -1/sqrt(2) >
...
 
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Jul 2010
7
0
Number 3 is also find the direction angle but since the fisrt and second problems have to do with quadrant i already firgured it out. Thank you
 
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