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How to solve cos 20 cos 40 cos 60 cos 80 |
| Answer» 1/2cos40cos20cos801/4*2cos40cos20cos801/4*(cos60+cos20)cos801/4*(1/2+cos20)cos801/4*(1/2cos80+cos80cos20)1/8*(2/2cos80+2cos80cos20)1/8*(cos80+cos60+cos100)1/8*(1/2+2cos180/2cos20)1/8*(1/2+2cos90cos20)1/8*(1/2+0)1/8*1/21/16answer | |