Question

What is the value of {(AxB).(C.D)x(AxB).(C.D)}? For the four vectors A, B, C and D, with A, B, C and D all lying in the same plane?

(a) i + j + k

(b) √3(i + j + k)

(c) 0

(d) -1(i + j + k)

This question was posed to me by my school principal while I was bunking the class.

I would like to ask this question from Dot Product and Cross Product topic in chapter Force Vectors of Engineering Mechanics

Answer 1

Correct answer is (c) 0

The explanation: Here we are trying to do the cross product of the two vectors in the same plane. Which will give us zero. While dot product of the same plane vector will give a scalar quantity, not zero.