If A = <4 ,3 ,-7 >, B = <5 ,8 ,-4 > and C=A-B, what is the angle between A and C?

Mar 13, 2016

87.75 deg, nearly.

Explanation:

A = $< 4 , 3 , - 7 > \mathmr{and} C = < - 1 , - 5 , - 3 >$

The $\angle$ between A and C[s
arc cos ( (A.C)/ (product of lengths A and C))

= $\arccos \left(\frac{2}{\sqrt{74} \sqrt{35}}\right) = \arccos \left(0.03930\right)$