Vectors - Please Help! "Find the angle between the vectors u<2,7>, v<1,-1>"

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Iheartpi13

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Vectors - Please Help! "Find the angle between the vectors u<2,7>, v<1,-1>"

Good afternoon,

I have this problem that I attempted and I'm not sure if I did it right. There is a debate between two answers and I don't know which is correct. The problem is: Find the angle between the vectors u<2,7>, v<1,-1>

I used the dot product rule and came up with an answer of 119.0 degrees. Other people are using the tangent function to find the angle of each vector and then subtracting the two. They came up with an answer of 240.9 degrees. I don't know which is right. Any help is appreciated :).

Thank you!
 
Iheartpi13 said:
Good afternoon,

I have this problem that I attempted and I'm not sure if I did it right. There is a debate between two answers and I don't know which is correct. The problem is: Find the angle between the vectors u<2,7>, v<1,-1>

I used the dot product rule and came up with an answer of 119.0 degrees. Other people are using the tangent function to find the angle of each vector and then subtracting the two. They came up with an answer of 240.9 degrees. I don't know which is right. Any help is appreciated :).

Thank you!
Click to expand...
Both the answers are correct - but I like your method.
 
Re: Vectors-Please Help!

How are both correct? :) I think I'm only supposed to have one answer
 
Iheartpi13 said:
Good afternoon,

I have this problem that I attempted and I'm not sure if I did it right. There is a debate between two answers and I don't know which is correct. The problem is: Find the angle between the vectors u<2,7>, v<1,-1>

I used the dot product rule and came up with an answer of 119.0 degrees. Other people are using the tangent function to find the angle of each vector and then subtracting the two. They came up with an answer of 240.9 degrees. I don't know which is right. Any help is appreciated :).

Thank you!
Click to expand...
What do the two answers add up to with a little rounding. What does this sum mean to you??
 
One thing I would do is draw the two vectors on a coordinate system. What does the angle between them look like?
 
Re: Vectors-Please Help!

They add up to 360 with a little rounding :) Does that sum mean that they are both possible answers? When I draw the vectors on a coordinate plane, it seems like the angle in between is smaller so I would say it's 119, but I'm not sure.
 
Re: Vectors-Please Help!

When I draw them, the angle in between looks smaller than 240.9 so I would say 119, but I'm not sure.
 
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