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

Question

1598 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-03-13T04:36:02

87.75 deg, nearly.

A = $< 4, 3, - 7 > and C = < - 1, - 5, - 3 >$ $< 4, 3, -7 > and C = <-1, -5, -3 >$

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

= $arccos (\frac{2}{\sqrt{74} \sqrt{35}}) = arccos (0.03930)$ $arccos (2/(sqrt74sqrt35))= arccos (0.03930)$

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