Question

The unit vactor parallel to the resultant of the vectors `vec(A)=4hat(i)+3hat(j)+6hat(k)` and `vec(B)=-hat(i)+3hat(j)-8hat(k)` is :-
A. `1/7 (3hat(i)+6hat(j)-2hat(k))`
B. `1/7 (3hat(i)+6hat(j)+2hat(k))`
C. `1/49 (3hat(i)+6hat(j)+2hat(k))`
D. `1/49(3hat(i)+6hat(j)-2hat(k))`

Answer 1

Correct Answer - A
Required unit vector
`=(vec(A)+vec(B))/(|vec(A)+vec(B)|)=(3hat(i)+6hat(j)-2hat(k))/sqrt(3^(2)+6^(2)+2^(2))=1/7 (3i+ 6hat(j)-2hat(k))`