Question

If a vector `(2hati+3hatj+8hatk)` is perpendicular to the vector `(4hatj-4hati+alpha hatk)`, then the value of `alpha` is :
A. -1
B. `1//2`
C. `-1//2`
D. 1

Answer 1

Correct Answer - B
`(2hati+3hatj+8hatk).(4hatj-4hati+alpha hatk)=0`
`-8-12+8alpha=0rArralpha=(+4)/(8)=(+1)/(2)`