sin10sin30sin50sin70的值= (是度）答案是1/16 我要过程

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sin10sin30sin50sin70的值=(是度）答案是1/16我要过程sin10sin30sin50sin70的值=(是度）答案是1/16我要过程sin10sin30sin50sin70的值=(

sin10sin30sin50sin70的值= (是度）答案是1/16 我要过程
sin10sin30sin50sin70的值= (是度）
答案是1/16 我要过程

sin10sin30sin50sin70的值= (是度）答案是1/16 我要过程
sin10sin30sin50sin70
=1/2*sin10*sin50*sin70
=1/2*sin10*cos20*cos40
=1/2*cos10*sin10*cos20*cos40/cos10
=1/4*sin20*cos20*cos40/cos10
=1/8*sin40*cos40/cos10
=1/16*sin80/cos10
=1/16*cos10/cos10
=1/16

sin10sin30sin50sin70
=(2sin10cos10/2cos10)sin30cos40cos20
=(sin20/2cos10)sin30cos40cos20
=[(1/2sin40)/2cos10]sin30cos40
=[(1/4sin80)/2cos10]sin30
=[(1/4sin80)/2sin80]sin30
=1/8sin30
=1/16

sin10sin30sin50sin70
=sin30（sin10sin50sin70）
=sin30（sin（60-10）sin10sin（60+10））
=sin30*（1/4sin30）
=1/16
三倍角公式

sin10sin30sin50sin70
=sin10cos10sin30sin50sin70/cos10
=sin20sin30sin50sin70/2cos10
=sin40sin30sin50/4cos10
=cos10/16cos10
=1/16

求值：sin10sin30sin50sin70 化简sin10sin30sin50sin70 sin10sin30sin50sin70= sin10sin30sin50sin70 求值 sin10sin30sin50sin70=多少 sin10sin30sin50sin70的值 求sin10sin30sin50sin70的值 求sin10sin30sin50sin70的值 sin10sin30sin50sin70的值= (是度）答案是1/16 我要过程 求sin10sin30sin50sin70的值(最好有过程),还有的就是sin20sin60sin100sin140=cos10cos30cos50cos70吗? (1/2)求值,1.sin10sin30sin50sin70 2.(2cos10-sin20)/cos20 3.(1+cos20)/2sin20 sin10sin30sin50sin70 =1/2sin1sin10sin30sin50sin70=1/2sin10sin50sin70=1/2sin10cos20cos40=1/2cos10cos10cos20cos40/cos10=1/4sin20cos20cos40/cos10=1/8sin40cos40/cos10=1/16sin80/cos10=1/16cos10/cos10=1/16第一步到第二步sim50sin70怎么变成了cos20