Hello! I am in Calc III, and I have a question. The answer sheet gives me a different answer than I have, but I feel that I am correct. Could you all point me one way or another?
Parallelogram with points: A(2, -1, 4); B(1,0,-1); C(1,2,3); D(2,1,8)
The question is.... what is the interior angle at B?
The answer sheet says use vectors AB and BC and comes up with 140.8 degrees.
I used vectors BA and BC and got 39.23 degrees.
Which one is correct? Thanks!
I did the calculation and got 140.768 or 140.8. Heres what I did, I found the vector from to and called it vector . I found by subtracting each corresponding point in from each point in to get vector .
I then did the same thing with from points to and called this vector . The subtraction resulted in: .
Then I computed the dot product, divided it by the product of the magnitudes of and and took the inverse cosine of this value, to find the angle between the vectors, like this:
I found the angle to be 140.8
I could be wrong, but check my work to make sure, dont assume I am right. Hope this helps