#1
|
|||
|
|||
µÃÕ⡳ÁÔµÔ
|
#2
|
|||
|
|||
$5-3sin3A$ ÁÒ¡·ÕèÊØ´àÁ×èÍ $sin3A = -1$
ä´éÇèÒ $3A = \frac{3\pi}{2} + 2n\pi$ ; $n \in I$ $........(1)$ áµè⨷Âì¡Ó˹´ÇèÒ $0 <= A <= \frac{4\pi}{3}$ ä´éÇèÒ $0 <= 3A <= 4\pi$ $.............(2)$ ¨Ò¡ $(1)$ áÅÐ $(2)$ $3A = \frac{3\pi}{2} , \frac{7\pi}{2} $ ´Ñ§¹Ñé¹ $A = \frac{\pi}{2} , \frac{7\pi}{6}$ áÅéÇ¡çËÒ૵¤ÓµÍº¢Í§ $cosA$ ¤ÃѺ 05 ÁԶعÒ¹ 2013 00:29 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 2 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ I am Me. |
#3
|
|||
|
|||
¢Íº¤Ø³ÁÒ¡¤ÃѺ
|
#4
|
|||
|
|||
áÅéÇ "àÁ×èÍ 2Sin X = Sec X ãËéËÒ¤èҢͧ Sin^4 X + Cos^4 X" ·ÓÂѧä§ÍèФÃѺ
»Å. ¢Í¶ÒÁ¹Ô´à´ÕÂÇ ã¹¢éÍ 2 ¢Í§¼Á äÁèÊÒÁÒöãªéÇÔ¸Õ (Sin^2 X + Cos^2 X)^2 = 1^2 ä´éãªéäËÁ¤ÃѺ (¤×ͼÁäÁèà¤ÂàËç¹ÃٻẺ¹ÕéàÅ áµèàËç¹à¾×è͹·Ó) |
#5
|
||||
|
||||
$\sin^2 x + \cos^2 x = 1$
$(\sin^2 x + \cos^2 x)^2 = 1^2$ ¶Ù¡áÅéǤÃѺ |
#6
|
||||
|
||||
"àÁ×èÍ 2Sin X = Sec X ãËéËÒ¤èҢͧ Sin^4 X + Cos^4 X" ·ÓÂѧä§ÍèФÃѺ
$2sinxcosx=1$ $sinxcosx=0.5$ $sinx^4+cosx^4=(sinx^2+cosx^2)^2-2sinx^2cosx^2=1-2(0.5)^2=0.5$ |
|
|