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![[Post New]](/templates/default/images/icon_minipost_new.gif) 18 Apr 2008 20:52:06 IST
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If cosx + cos2 x =1, then the value of sin12 x + 3 sin10 x + 3 sin8x + sin6 x -1 is?? This question was given in VITEEE last year....solve dis plzzz
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18 Apr 2008 21:09:47 IST
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is it 3cos^3x
cosx=sin^2x
sin^12x+3sin^10x+3sin^8x+sin^6x-1
= cos^6x+sin^6x-1+3sin^10x+3sin^8x
=3sin^10x+3sin^8x
=3sin^6x(sin^2x+sin^4x)
=3cos^3x
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19 Apr 2008 06:26:57 IST
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0..
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Diamonds r formed under greatest pressures..
so r the champs.
Kriteesh..
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19 Apr 2008 06:34:15 IST
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sin x + sin 2 x= 1
sin x = cos 2 x
cos 12 x + 3 cos 10 x + 3 cos 8 x + cos 6 x
= sin 6 x + 3 sin 5 x + 3 sin 4 x + sin 3 x
= ( sin 2 x + sin x ) 3
= 1
So 1 - 1 = 0
Ans .
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