Question #88d58

1 Answer
May 15, 2017

Zero.

Explanation:

This is one case of Scalar triple product :-

A.(B x C)

Geometrically A, B, C are the there vectors defining there sides of a parallelepiped.
and the scalar triple product of these vectors give it's volume.

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So now to evaluate, (C x D).D

When we evaluate, C x D, we get a vector(lets say A) which is perpendicular to vector C and D.

And finding the dot product of A.D, we get,

A.D=|A||D|cos90--------( cos90 because A is perpendicular to D)

we know cos90=0.

So, A.D=0.

rArr (C x D).D = 0