Question

pls. answer this one ​

Answer 1

Solution:-Simply take out the dot product directly and then by using formula and then equate both

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

=2×1+1×0+(-1)×(-1)=3.......i)

also,we know,dot product=|A||B|cos∅

now here

|A|=(4+1+1)^1/2

=√6

|B|=(1+1)^1/2

=√2

so,

dot product=√2×√6×cos∅

also, we know that

dot product=3

so,

√2×√6×cos∅=3

2√3cos∅=3

cos∅=√3/2

cos∅=cos30°

∅=30°

hence angle between these two Vectors will be 30°