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If sin ^(3) x sin 3 x=sum(r=0)^(n) a(r)...

If ` sin ^(3) x sin 3 x=sum_(r=0)^(n) a_(r) cos r x` is an identity in `x,` then `n=`

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3

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4

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6

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9

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HIMALAYA PUBLICATION-MEASUREMENT OF ANGLES, TRIGONOMETRIC RATIOS AND RELATION BETWEEN SIDES AND ANGLES OF A TRIANGLE-QUESTION BANK
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  3. If sin ^(3) x sin 3 x=sum(r=0)^(n) a(r) cos r x is an identity in x, ...

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  17. 3(sinx-cosx)^(4)+6(sinx+cosx)^(2)+4(sin^(6)x+cos^(6)x)=

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  19. If |(1+sin^(2)theta, cos^(2)theta, 4 sin 2 theta),(sin^(2) theta, 1+co...

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