Question

`0.4hat(i)+0.8hat(j)+chat(k)` represents a unit vector, when c is :-
A. 0.2
B. `sqrt(0.2)`
C. `sqrt(0.8)`
D. 0

Answer 1

Correct Answer - B
Let `vec(A)=0.4hat(i)+0.8hat(j)+Chat(k)` is a unit vector
then `" " |vec(A)|=1`
`rArr" " sqrt(0.16+0.64+C^(2))=1`
`rArr " " 0.80+c^(2)=1^(2)`
`rArr " " C^(2)=0.2` ltbr. C=sqrt(0.2)`
` " " C=sqrt(0.2)`