# What is the angle between #<-4 , 0 , -1 > # and # < 8 , 6 , 3 > #?

##### 1 Answer

Feb 16, 2016

144.4 deg, nearly.

#### Explanation:

Let the vectors be called AC and AB.

Then the vector BC = AB - AC = <12, 6, 4>.

The sides a, b and c of the

The angle at A is arccos (( b.b + c.c - a.a ) / (2bc).= arccos( -0.8131) =144.4 deg.