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![[Post New]](/templates/default/images/icon_minipost_new.gif) 16 Mar 2008 08:33:43 IST
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cos x-1+cos-1y +cos-1 z =
then s t
x^2 +y^2+z^2 +2xyz=1
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16 Mar 2008 09:05:08 IST
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cos -1 x + cos -1 y = - cos -1 z
So cos -1 [ xy -  (1-x2)(1-y2) ] = cos -1 (-z)
So xy - (1-x2)(1-y2) = -z
or (xy+z) 2 = (1-x2)(1-y2)
or x2+ y2 + z2 + 2xyz = 1
@ magaishwariya with respect to a previous question, a solution should be the shortest possible,i dont find any reason for unnecessarily making our answers long and complicated! After all we are all looking for the shortest possible and the best solution.That's our ultimate motive, otherwise a problem can be approached in n number of ways.
I didn't know NCERT is defining Maths in its own ways!!
[ edit : w.r.t next post]
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16 Mar 2008 09:09:25 IST
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ur not supposed to use the above formula in boards
rite?
if u do ull loose marks as that formula is not mentioned in NCERT
so convert to tan and then proceed
u need marks in board not the shortest possible solution
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B.Tech CSE
NIT Trichy |
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16 Mar 2008 17:38:23 IST
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no offence meant to any1, but is this site called goiit.com or gocbseboardexam.com?! 
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JEE and OLYMPIA INFINATUM
http://iit-redefined.theforum.name/index.php
join the revolution!! |
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16 Mar 2008 17:44:29 IST
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thats what i was thinking, everyone is posting board problems here
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16 Mar 2008 18:16:54 IST
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and Olympiad problems. 
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Let us learn to dream, gentlemen, and then perhaps we shall learn the truth.
- August Kekule |
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16 Mar 2008 18:28:23 IST
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see man board problems are easy so doing easy problems isnt going to improve the skill is it. Olympiad problems are a bit tricky and they give newer methods n improve one's skill so its good if we do them No offense meant to the board problems posted  |
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16 Mar 2008 19:48:52 IST
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Oh madness calm down!! and if any formula is not allowed in board i prefer that you derive it and dont use the formula as such!!!then ofcourse no offence meant!!!
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