Q. If a vector 2î + 3ĵ + 8k̂ is perpendicular to the vector 4ĵ − 4î + αk̂, then the value of α is :
A) −2
B) 1/2
C) −1/2
D) 2
Explanation
[Solution from source] Perpendicular vectors have zero dot product: 2(−4) + 3(4) + 8α = 0, so 4 + 8α = 0 and α = −1/2. Ignoring the sign of the î component gives the wrong −2 or 2. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.