# calculus

Find the angle ABC, if A = (4, –3, –1), B = (0, 0, 0) and C = (–2, –3, 5)

Could you lead me in the right direction I don't know where to start

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1. If you have used vectors, you can
1. calculate the vectors AB and CB.
2. Calculate the inner product (or dot product) AB.CB and the magnitudes of AB and CB.
3. Cos(θ) = AC.CB/(|AB|*|CB|)

You can also calculate by trigonometry by calculating the lengths of each of the three sides, and use cosine rule to solve for angle B.
AB (dot) CB equals

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