(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

If A = 1i + 2j + 3k and B = 1i + 2k, and if C = A X B, then the angle between the vector A and the vector C is:

2. Relevant equations

AxB = ((a2b3-a3b2)i + (a3b1-a1b3)j + (a1b2-a2b3)k)

A·B = ABcosθ = AiBi + AjBj + AkBk

3. The attempt at a solution

I got C = 4i + j -2k and A = 1i + 2j + 3k

A·C = 4i + 2j - 6k with a magnitude of 7.48

then I used the magnitude of A and C individually to get 3.74 and 4.58 respectively.

The I used the equation cos^{-1}(7.48/(3.74 x 4.58)) = θ

θ = 64.11 degrees. The actual answer is 90 degrees. What am I doing wrong?

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# Homework Help: Angle Between Vectors

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