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if cos x=-4/5 , where x in [ 0,pi] t...

if `cos x=-4/5 ,` where ` x in [ 0,pi]` then the value of ` cos (x/2)` is equal to

A

`(1)/(10)`

B

`(2)/(5)`

C

`(1)/(sqrt(10))`

D

`-(2)/(5)`

Text Solution

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The correct Answer is:
C
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