Science:Math Exam Resources/Courses/MATH152/April 2010/Question A 08
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Question A 08 

What is where is the angle between the vectors [1,2,3] and [1,5,2]? 
Make sure you understand the problem fully: What is the question asking you to do? Are there specific conditions or constraints that you should take note of? How will you know if your answer is correct from your work only? Can you rephrase the question in your own words in a way that makes sense to you? 
If you are stuck, check the hint below. Consider it for a while. Does it give you a new idea on how to approach the problem? If so, try it! 
Hint 

Recall that dot products and cross products can be written in terms of angles between vectors. Which one of those two products (dot or cross) uses cosine? 
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Solution 

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Please rate my easiness! It's quick and helps everyone guide their studies. We can write the dot product between two vectors u and v as where is the angle between vectors u and v. Therefore we have that Here our two vectors are We have that and that Therefore, 