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#1
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ú¡Ç¹ªèǾÔÊÙ¨¹ì¢éÍʧÊÑÂàËÅèÒ¹ÕéãËé·Õ¤ÃѺ
µÍ¹¹Õé¼Á¡çÇèÒ¨ÐàÃÕ¡ÇèÒàÍ¡Åѡɳì¹Ð¤ÃѺ áµèÁͧä»ÁÒàËÁ×͹ÊÙµÃÅÑ´ÁÒ¡¡ÇèÒ
1. $asinx + bcosx$ ¨ÐÁÕ¤èÒÁÒ¡·ÕèÊØ´ ¤×Í $\sqrt{a^2 + b^2}$ 2.$asinx + bcosx$ ¨ÐÁÕ¤èÒÁÒ¡·ÕèÊØ´¤×Í $x = arctan(\frac{b}{a})$ |
#2
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¤Øé¹æÇèÒ¨Ðà¡ÕèÂǡѺ¨Ó¹Ç¹àªÔ§«é͹
Åͧà¢éÒä»Íèҹ㹹Õé¡è͹äËÁ¤ÃѺ....àÊÃÔÁ»ÃÐʺ¡Òó줳ԵÈÒʵÃìªØ´·Õè ñù....ÃÙéÊÖ¡ÇèÒ¨ÐäÁèÁÕ¡ÒþÔÊÙ¨¹ì
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"¶éÒàÃÒÅéÁºèÍÂæ ã¹·ÕèÊØ´àÃÒ¨ÐÃÙéÇèÒ¶éÒ¨ÐÅéÁ ÅéÁ·èÒä˹¨Ðà¨çº¹éÍ·ÕèÊØ´ áÅÐÃÙéÍÕ¡ÇèÒµèÍä»·ÓÂѧ䧨ÐäÁèãËéÅéÁÍÕ¡ ´Ñ§¹Ñ鹨§ÍÂèÒ¡ÅÑÇ·Õè¨ÐÅéÁ"...ÍÒ¨ÒÃÂìÍӹǠ¢¹Ñ¹ä·Â ¤ÃÑé§áá㹪ÕÇÔµ·ÕèÊͺ¤³ÔµÊÁÒ¤Á¤³ÔµÈÒʵÃìàÁ×èÍ»Õ2533...¼Áä´éá¤è24¤Ðá¹¹(¨Ò¡ÃéͤÐá¹¹) |
#3
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ÍéÒ§ÍÔ§:
$a\sin x + b\cos x = \sqrt{a^2+b^2}(a/\sqrt{a^2+b^2}\sin x+b/\sqrt{a^2+b^2}\cos x)$ ÊÁÁµÔãËé $\cos A = a/\sqrt{a^2+b^2}$ ´Ñ§¹Ñé¹ â¨·Âì = $\sqrt{a^2+b^2}\sin(x+A)$ «Ö觨ÐÁÕ¤èÒÊÙ§ÊØ´àÁ×èÍ $\sin(x+A) = 1$ áÅÐàÁ×èÍ $\sin(x+A) = 1$ áÅéǨÐä´é $x+A = n\pi + \pi/2 \Rightarrow x = n\pi + \pi/2 - A = n\pi + \pi/2 - \arctan(b/a)$ ¡Ã³Õ¾ÔàÈɶéÒ¨ÐËÒ¤èÒ x ÁÒ´ÙÊÑ¡ 1 ¤èÒ àÅ×Í¡ n = 0 ¨Ðä´é $x = \pi/2 - \arctan(b/a) = arctan(a/b)$ áµè¶éÒÊÁÁµÔãËé $\sin A = a/\sqrt{a^2+b^2}$ ¨Ðä´é $a\sin x + b\cos x = \sqrt{a^2+b^2}\cos(x-A)$ «Ö觨ÐÁÕ¤èÒÊÙ§ÊØ´àÁ×èÍ $\cos(x-A) = 1 \Rightarrow x - A = 2n\pi \Rightarrow x = 2n\pi + A = 2n\pi + \arctan(a/b)$ 㹷ӹͧàé´ÕÂǡѹ ¶éÒàÅ×Í¡ n = 0 ¨Ðä´é $x = \arctan(a/b)$ à»ç¹¤èÒ˹Ö觷Õè·ÓãËé $a\sin x + b\cos x$ ÁÕ¤èÒÊÙ§ÊØ´ 18 ¡Ã¡®Ò¤Á 2010 20:45 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 1 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ ★★★☆☆ |
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