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If a line makes angles alpha ,beta , ga...

If a line makes angles ` alpha ,beta , gamma ` with the co-ordinates axes,
then ` cos 2alpha +cos 2beta +cos 2gamma ` is :

A

3

B

` -2`

C

` 2`

D

` -1`

Text Solution

Verified by Experts

The correct Answer is:
D
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