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Prove that (i) " cos " ((pi)/(4) + x...

Prove that
`(i) " cos " ((pi)/(4) + x) + " cos " ((pi)/(4)- x) =sqrt(2) " cos " x`
`(ii) " cos " ((3pi)/(4) + x) - "cos " ((3pi)/(4)-x) =- sqrt(2) " sin " x`

A

`sqrt2 sin ^(2) x`

B

`sqrt2 sin x`

C

`sqrt2 cos ^(2) x`

D

`sqrt2 cos x`

Text Solution

Verified by Experts

The correct Answer is:
D
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TARGET PUBLICATION-TRIGONOMETRIC FUNCTIONS OF COMPOUND ANGLES -COMPETITIVE THINKING
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