Finding an angle between two vectors

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    Angle Vectors
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Homework Help Overview

The problem involves finding the angle between two vectors, u and v, using the dot product and magnitudes of the vectors. The original poster attempts to calculate the angle but receives feedback indicating their answer may be incorrect.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the possibility that the original poster's answer might be in the wrong unit (degrees vs. radians) and question the lack of specification in the assignment regarding the unit of measurement.

Discussion Status

The discussion is ongoing, with participants exploring the implications of angle measurement units and sharing personal experiences related to the conventions of angle measurement in their studies. There is no explicit consensus on the correct approach yet.

Contextual Notes

Participants note that the assignment does not specify whether angles should be reported in degrees or radians, which adds to the confusion. There is also mention of the constraints of the webwork assignment format, which limits verification of answers.

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Homework Statement



Find the angle between the vectors u=[4 -4 -3] and v=[2 2 -3].


Homework Equations



theta = arccos(u . v)/(|u||v|)


The Attempt at a Solution



arccos[(8+(-8)+9)/(sqrt(41)*sqrt(17))]= 70.068 degrees. According to the online homework, it is wrong...and I and stumped.
Any help would be appreciated!

Thanks!
 
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Check if their answer isn't perhaps in radians.
 
Well the thing is, it is a webwork assignment, so you can't really check the answer. And the question was not specfic for degrees or radians.:frown: Well, what counts is that I know I did it right. Thanks phyzmatix
 
As a rule of thumb (well, this definitely holds for where I'm studying anyway) angles are ALWAYS in radians, unless specifically stated otherwise. It took me a while to get used to this also as we never did radians in school.
 

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