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1/
a/ 2sin 2 x-1=0 б. sin 2 x - 2 sin x -3=0 в. cos3x+ cos 5x=0
2sin=1 sin 2 x - 2 sin x=3 2cos 4x cos x =0
sin x= 1/2 x э ф cos 4x cos x=0
x= arsin(1/2) 1/ cos 4x=0
x= п/6 x= п/8 +кп/4
k=z
2/cos x=0
п/2 +пк
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