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If 0 le x le pi and cosx=-4/5 then cos(x...

If `0 le x le pi` and `cosx=-4/5` then `cos(x/2)` is equal to:

A

`3/sqrt10`

B

`-3/sqrt10`

C

`1/sqrt10`

D

none of these

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JBD PUBLICATION-TRIGNOMETRIC FUNCTIONS-EXAMPLE
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