19. What is the cosine of the angle between the vectors <-2,1,2> and <6,3,-2> in R3 ?
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A. –13/10 |
B. –10/13 |
C. –13/21 |
|
D. 3/7 |
E. 19/21 |
Solution: The answer is C
By definition, the cosine of the angle, theta, between any two vectors a and b, in R3 is given by the following equation:
Where the numerator of the above equation is the dot product of the two vectors and the denominator is the product of their magnitudes.
Thus, the cosine of the angle between the two given vectors is,
