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Let the unit vectors vec a and vec b be ...

Let the unit vectors `vec a` and `vec b` be perpendicular to each other and the unit vector `vec c` be inclined at an angle `theta` to both `vec a` and `vec b`. If ` vec c = x vec a + y vec b + z (vec a xx vec b)` then,

A

A. `x = cos theta, y = sin theta, z = cos 2 theta`

B

B. `x = sin theta, y = cos theta, z= -cos 2 theta`

C

C. `x = y = cos theta, z^(2) = - cos 2 theta`

D

D. `x = y = cos theta, z^(2) = -cos 2 theta`

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The correct Answer is:
D
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