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à¤Ã×èͧÁ×ͧ͢ËÑÇ¢éÍ | ¤é¹ËÒã¹ËÑÇ¢é͹Õé |
#1
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͹ءÃÁ+µÃÕ⡳¤ÃѺ
¡Ó˹´ãËé$0<\alpha ,\beta <\frac{\pi }{2}$áÅÐ$tan(\alpha +\beta )=tan(\alpha )+cot(\alpha )+tan(\beta )+cot(\beta )$áÅéÇ͹ءÃÁ͹ѹµì$1+tan(\alpha )tan(\beta )+tan^2(\alpha )tan^2(\beta )+tan^3(\alpha )tan^3(\beta )+...$ ÅÙèà¢éÒÊÙè¤èÒã´
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#2
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ªÔ§µÍº
1) ¨Ò¡.......$tan(\alpha +\beta )=tan\alpha +cot\alpha +tan\beta +cot\beta $
$tan(\alpha +\beta )=tan\alpha +\frac{1}{tan\alpha }+tan\beta +\frac{1}{tan\beta }$ $tan(\alpha +\beta )=\frac{tan^2\alpha +1}{tan\alpha } +\frac{tan^2\beta +1}{tan\beta }$ $tan(\alpha +\beta )=\frac{sec^2\alpha}{tan\alpha } +\frac{sec^2\beta}{tan\beta }$ $\therefore tan(\alpha +\beta )=\frac{2}{sin2\alpha } +\frac{2}{sin2\beta }$ 2) ¨Ò¡.......$tan(\alpha +\beta )=\frac{tan\alpha +tan\beta }{1-tan\alpha tan\beta }$ $1-tan\alpha tan\beta=\frac{tan\alpha +tan\beta}{tan(\alpha +\beta )}$ $tan\alpha tan\beta=1-\frac{tan\alpha +tan\beta}{tan(\alpha +\beta )}$ $tan\alpha tan\beta=\frac{tan(\alpha +\beta )-tan\alpha -tan\beta }{tan(\alpha +\beta )}$ áÅШҡ 1) á·¹¤èÒ $tan(\alpha +\beta )$ $tan\alpha tan\beta=\frac{\frac{2}{sin2\alpha}+\frac{2}{sin2\beta }-\frac{1-cos2\alpha }{sin2\alpha }- \frac{1-cos2\beta }{sin2\beta } }{tan(\alpha +\beta )}$ $tan\alpha tan\beta=\frac{\frac{cos2\alpha +1}{sin2\alpha }+\frac{cos2\beta +1}{sin2\beta } }{tan(\alpha +\beta )}$ $tan\alpha tan\beta=\frac{\frac{1}{tan\alpha }+\frac{1}{tan\beta } }{tan(\alpha +\beta )} $ $tan\alpha tan\beta=\frac{\frac{tan\alpha +tan\beta }{tan\alpha tan\beta } }{\frac{tan\alpha +tan\beta }{1-tan\alpha tan\beta} } $ $tan\alpha tan\beta=\frac{1-tan\alpha tan\beta}{tan\alpha tan\beta}$ 3) ¨Ò¡ 2) ãËé $A=tan\alpha tan\beta$ $A=\frac{1-A}{A}$ $A^2=1-A$ $A^2+A-1=0$ $A=\frac{-1\pm \sqrt{6} }{2} $ áµè........¤èÒ $A=tan\alpha tan\beta$ áÅÐ $0<\alpha ,\beta <\frac{\pi }{2}.....\therefore $ ¤èÒ $A$ à»ç¹ $+$ $\therefore A=\frac{-1+ \sqrt{6} }{2}$ 4) ¤èÒ $A=tan\alpha tan\beta<1$ ͹ءÃÁÅÙèà¢éÒ.... Áռźǡà»ç¹......$\frac{1}{1-\frac{-1+ \sqrt{6} }{2}}$ $\frac{2}{3-\sqrt{6} } $ |
#3
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#2 Åͧàªç¤´Ù¤ÃѺ ¤ÓµÍº¤×Í $(\frac{\sqrt5+1}{2})^2$
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Hope is what makes us strong. It's why we are here. It is what we fight with when all else is lost. 24 ¾ÄȨԡÒ¹ 2014 15:26 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 2 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ FranceZii Siriseth |
#4
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¢Íá¡éä¢
ãªè¤ÃѺ......¤Ø³¿ÃÒ¹«Ô ÊÔÃÔàÊÊ(ÍèÒ¹¶Ù¡ËÃ×Íà»ÅèÒ¤ÃѺ)
µéͧµÍº.......$\frac{2}{3-\sqrt{5} }=(\frac{\sqrt{5}+1}{2})^2$.......¢Íº¤Ø¹ÁÒ¡¤ÃѺ |
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