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November 13th, 2008, 04:18 PM   #1
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half angle ..

show that tan 22.5 = square root 2 -1


thanks for any help ..
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November 13th, 2008, 05:21 PM   #2
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Re: half angle ..

Google: Half angle formula.
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November 13th, 2008, 06:12 PM   #3
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Re: half angle ..

It may help to remember that tan(x) = sin(x)/cos(x)
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November 13th, 2008, 06:52 PM   #4
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Re: half angle ..

Quote:
Originally Posted by cknapp
It may help to remember that tan(x) = sin(x)/cos(x)
It might be better to know that tan(x/2) = (1-cos(x))/sin(x) = sin(x)/(1+cos(x)) ...take your pick.
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November 14th, 2008, 01:46 AM   #5
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Re: half angle ..

wait ..
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November 14th, 2008, 02:18 AM   #6
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Re: half angle ..

alright i got it .. thx all
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