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Ask community Community Discussion Question: trigo 30
Reply Forum Index -> Trignometry originally posted here on IIT-JEE / AIEEE community   
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[Post New] 21 Mar 2008 09:23:25 IST
   Subject: trigo 30
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ankur khurana (527)

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Olaaa!! Perrrfect answer. 87  bad job dude!! I dont approve of this answer! 1  [135 rates]
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evaluate
tan9 - tan27 - tan63 + tan81

i am getting answer as 0 but given answer is 4
adversities cause some men to break other to break records............i m of the other type....... :-)
    
[Post New] 21 Mar 2008 12:04:33 IST
   Subject: Re:trigo 30
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sreeraman nagasubramaniyan (3058)

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[tex] \\ \\ (\tan9+\tan81) - (\tan27+\tan63) \\ \\ (\tan9+\frac{1}{\tan9}) - (\tan27+\frac{1}{\tan27}) \\ \\ (\frac{\sec^29}{\tan9}) - (\frac{\sec^227}{\tan27}) \\ \\ \frac{\sec^29}{\tan9} = \frac{1}{\sin9 \cos9} = \frac{2}{\sin18} , \frac{\sec^227}{\tan27} = \frac{1}{\sin27 \cos27} = \frac{2}{\sin54} \\ \\ (\frac{2}{\sin18}) - (\frac{2}{\sin54}) \\ \\ \sin18 = \frac{\sqrt{5} - 1}{4} , \sin54 = \frac{\sqrt{5} + 1}{4} \\ \\ \frac{8}{\sqrt{5} - 1} - \frac{8}{\sqrt{5}+1} = \frac{16}{4} = 4
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[Post New] 21 Mar 2008 13:34:50 IST
   Subject: Re:trigo 30
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Abhijith (2371)

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Just a continuation of sboosy's post without making use of values of and .
Guide to latex:
http://www.goiit.com/posts/list/community-shelf-a-guide-to-latex-48056.htm

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