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If A+B+C=180^(@) " then " cos 3A + cos 3...

If `A+B+C=180^(@) " then " cos 3A + cos 3B+ cos 3C= `

A

`4 cos""(3A)/(2) cos""(3B)/(2) cos""(3C)/(2) `

B

`-4 cos""(3A)/(2) cos""(3B)/(2) cos""(3C)/(2) `

C

`1-4 cos""(3A)/(2) cos""(3B)/(2) cos""(3C)/(2) `

D

`1-4 sin""(3A)/(2) sin""(3B)/(2) sin""(3C)/(2) `

Text Solution

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The correct Answer is:
D
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DIPTI PUBLICATION ( AP EAMET)-TRIGONOMETRIC RATIOS AND IDENTITIES -EXERCISE 1 E ( TRIGONOMETRIC IDENTITIES )
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