упростить cos 22 + cos 24 + cos 26 + cos 28=
cos 22 + cos 24 + cos 26 + cos 28=(cos22+cos28)+(cos24+cos26)=
=2cos((22+28)/2)*cos((28-22)/2)+2cos((24+26)/2)*cos((26-24)/2)=
=2cos25*cos3+2cos25*cos1=2cos25(cos3+cos1)=2cos25*2cos((3+1)/2)*cos((3-1)/2)=
=4cos25*cos2*cos1
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cos 22 + cos 24 + cos 26 + cos 28=(cos22+cos28)+(cos24+cos26)=
=2cos((22+28)/2)*cos((28-22)/2)+2cos((24+26)/2)*cos((26-24)/2)=
=2cos25*cos3+2cos25*cos1=2cos25(cos3+cos1)=2cos25*2cos((3+1)/2)*cos((3-1)/2)=
=4cos25*cos2*cos1