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(i) if sin x= (1)/(3) find the value ...

(i) if sin `x= (1)/(3) ` find the value of sin 3x (ii) if cos ` x= (1)/(2) ,` find the value of cos 3x

Text Solution

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(i) sin 3x =(3 sin x -4 `sin^ (3)`x)
`={(3x (1)/(3)) -4 xx ((1)/(3))^(3) }= (1-(4)/(27)) = (23)/(27)`
(ii) cos 3x =( 4 `cos^(3)` x -3 cos x)
`={(4 xx (1)/(8) ) - (3 xx (1)/(2))}= ((1)/(2) -(3)/(2)) =-1`
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