Question

For what value of A, is vector A=ai cap-2j cap+k cap are perpendicular to the vector B=2ai cap+aj cap-4k cap? ​

Answer 1

Explanation:

The two vectors, say A( 2i — 3j + 4k) and B(ai + 6j — 8k) are perpendicular, which means angle between them is 90°.

x = 90°

We know that

A.B = AB cos x

A.B = AB cos 90°

A.B = AB * 0

A.B= 0

(2i-3j+4k).(ai+6j-8k)= 0

On solving, we get 2a-18-32=0

a = 25