Question

5. Find the angles between the following pairs of
vectors :
(1) A =î+j^+ k^ B=-2i^-2j^-2k^

Answer 1

Explanation:

A.B=(i+j+k).(-2i-2j-2k)

=-2-2-2

A.B =-6.............(1)

|A|=√(1)²+(1)²+(1)²=√1+1+1=√3

|B|=√(-2)²+(-2)²+(-2)²=√4+4+4=√12

so, |A||B|=√3.√12=√36=6

now,

cos theta=A.B/|A||B|

=-6/6

=-1

SO, theta=0°