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A.Maths Compound angle
發問:
Solve the following equation for 0 degree
最佳解答:
cos x + cos 2x + cos 3x + cos 4x = 0 cosx+cos3x+cos2x+cos4x=0 2cos2xcosx+2cos3xcosx=0 cosx(cos2x+cos3x)=0 cosx[2cos(5x/2)cos(x/2)]=0 cosx=0 or cos(5x/2)=0 or cos(x/2)=0 x=90?,270?or 5x/2=90?,270?,450?630?,810?or x/2= 90? x=36?,90?,108?180?252?,270?or 324?
其他解答:4E350C6F8B48ECA2
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