Q. 174.3( 20 Votes )

# Let and be two unit vectors and q is the angle between them. Then is a unit vector if

A.

B.

C.

D.

Answer :

let the two unit vectors are and is the angle between.

Then

Then this is () is unit vector if

scalar product is cumulative.

Hence, () is unit vector if .

The correct answer is (D).

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