大师作文网cos10*cos20*cos30
来源：学生作业帮 编辑：大师作文网作业帮 分类：数学作业 时间：2024/11/11 08:02:13
cos10*cos20*cos30
如题,
如题,
是 cos 10° cos 20° cos 30°
= = = = = = = = =
由积化和差公式,得
cos 20° cos 10° = [ cos (20°+10°) +cos (20°-10°) ] /2
= (cos 30° +cos 10°) /2,
= √3 /4 +(1/2)cos 10°.
所以 cos 10° cos 20° cos 30° = [ √3 /4 +(1/2)cos 10° ] (√3 /2)
= 3 /8 +(√3 /4 )cos 10°.
= = = = = = = = =
由积化和差公式,得
cos 20° cos 10° = [ cos (20°+10°) +cos (20°-10°) ] /2
= (cos 30° +cos 10°) /2,
= √3 /4 +(1/2)cos 10°.
所以 cos 10° cos 20° cos 30° = [ √3 /4 +(1/2)cos 10° ] (√3 /2)
= 3 /8 +(√3 /4 )cos 10°.
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