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![[Post New]](/templates/default/images/icon_minipost_new.gif) 19 Apr 2008 13:00:47 IST
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if (cos4a)/x + (sin4a)/y=1/(x+y)
then dy/dx =??
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"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein |
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19 Apr 2008 16:34:49 IST
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what's the ans.I got a complex expression but we can simplify them
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MAKING A MISTAKE IS HUMAN BUT REPEATING IT IS IDIOTIC. |
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19 Apr 2008 16:40:47 IST
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Simplify and post your answer
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19 Apr 2008 16:48:38 IST
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-(1+cos4a(1+y/x)2 ) / (1+sin4a(1+x/y)2 )
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19 Apr 2008 17:22:07 IST
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(cos4a)/x + (sin4a)/y=1/(x+y)
y(cos4 a) + x (sin4 a) = xy /x+y
differentiating
we get
dy/dx cos4 a + sin4 a = [y+xdy/dx ] [x+y] - [1+dy/dx] [ xy] /(x+y)2
dy/dxcos4 a+sin4 a = [xy + x2 dy/dx + y2 +xydy/dx - xy - xydy/dx ] /(x+y)2
dy/dx cos4a + sin4 a = [x2 dy/dx + y2 ] /(x+y)2
dy/dxcos4 a (x+y)2 +sin4 a(x+y)2 = x2 dy/dx + y2
dy/dx [ cos4 a(x+y)2 -x2 ] = y2 - sin4 a (x+y)2
dy/dx = [y2 -sin4 a(x+y)2 ] / [cos4 a(x+y)2 -x2 ]
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19 Apr 2008 17:35:16 IST
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please someone tell
is my approach right
and answert too
plzzz someone reply
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19 Apr 2008 18:34:36 IST
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is ans tan2a if yes then pls let me know
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19 Apr 2008 19:00:36 IST
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the answer is tan^2 (a)
but plz show the steps
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"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein |
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19 Apr 2008 19:35:33 IST
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where have i gone wrong
plzzzz let me know
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19 Apr 2008 19:50:36 IST
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@ganesha
hey if i wud have known then y wud 1 ask d question?
the only thing i know is this is objective type question.so it can be so long.use substitution or other trick.
but i dont know :(
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"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein |
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19 Apr 2008 19:54:15 IST
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ok lemme try again
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20 Apr 2008 20:05:52 IST
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look the trick involved in this quest is u need to solve the eq. provided in quest first and that will simplify it as xsin2 a=ycos2a,now simply differenciate both the sides and there u r
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20 Apr 2008 20:12:43 IST
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can u explain it in lil bit more detail
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"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein |
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20 Apr 2008 20:29:36 IST
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cos^4a/x+sin^4a/y=1/x+y
ycos^4a+xsin^4a/xy= (sin^2a+cos^2a)^2/x+y
xycos^4a + y^2cos^4a + xysin^4a + x^2sin^4a= xysin^4a + xycos^4a +2xysin^2acos^2a
(ycos^2a-xsin^2a)^2=0
ycos^2a=xsin^2a
y=xtan^2a
dy/dx=tan^2a
now rate me
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20 Apr 2008 20:33:46 IST
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if u can solve it in ne other way i'll give 5 salutes to u
definitely
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"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein |
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