cos2xsin2x
sin2x,cos2x,tan2x·Ö±ðÊǶàÉÙ?
sin2x=2sinxcosx¡£cos2x=(cosx)^2-(sinx)^2=2(cosx)^2-1=1-2(sinx)^2¡£tan2x=2tanx/(1-(tanx)^2)¡£±¶½Ç¹«Ê½£¬ÊÇÈý½Çº¯ÊýÖзÇ...
ÊýѧÈý½Çº¯Êý»»Ëãsin 2x = cos 2x = µÈµÈ»»Ë㹫ʽ...
sin 2x = 2sinxcosxcos2x=cosx^2-sinx^2.
sin2x+cos2xÔõô»¯¼ò - °Ù¶È¾Ñé
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ΪʲôSin2xµÄµ¼ÊýÊÇ2cos2x¶ø²»ÊÇcos2x?
\sin2xÍâ²ãº¯ÊýΪy=\sin t,Äڲ㺯ÊýΪt=2x£¬\\¸ù¾ÝÁ´Ê½·¨Ôò£º\\\frac{dy}{dx}=\frac{dy}{dt}\cdot\frac{dt}{dx}=\cos t\cdot2=...
cos2xÓësin2xµÄ¹ØÏµÊÇʲô?
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Èý½Çº¯ÊýÖÐcos2x,sin2x¡µÈ¹«Ê½ÊÇ?
= (cosx)^2 - (sinx)^2 = 2(cosx)^2 - 1 = 1 - 2(sinx)^2sin2x = 2sinxcosxcos2X=(cosX)^2-(sinX)^2=2*(cosX)^2-1=1-2*(sinX)^2sin2x=2...
Ϊʲôsin2xµÄµ¼ÊýÊÇ2cos2x?
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Çóº¯Êýy=sin2x - cos2xµÄ×î´óÖµºÍ×îСֵ.
½â´ð:½â:¡ßy=sin2x-cos2x=2(22sin2x-22cos2x)=2sin(2x-¦Ð4),¡àµ±sin(2x-¦Ð4)=1ʱ,ymax=2,µ±sin(2x-¦Ð4)=-1ʱ,ymin=-2.
¹òÇó¡Òcos2x/sin^2xcos^2xdx Ê®Íò»ð¼±!
sin^2xcos^2x=1/4(2sinxcosx)^2=1/4sin2xÔʽ=¡Òcos2x/sin^2xcos^2xdx=¡Òcos2x/(1/4sin2x)dx=¡Ò2/sin2xd(sin2x)=2lnsin2x+C