求证Sin10° *Sin30° *Sin50° *Sin70° =1/16
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求证Sin10° *Sin30° *Sin50° *Sin70° =1/16
要快哦明天早上要 谢
要快哦明天早上要 谢
左边=sin10*sin30*cos(90-50)*cos(90-70)
=sin10*1/2*cos20*cos40
=1/2*sin10cos10cos20cos40/cos10
=(1/2)*8sin10cos10cos20cos40/8cos10
=(1/16)*4sin20cos20cos40/cos10
=(1/16)*2sin40cos40/cos10
=(1/16)*sin80/sin80
=1/16=右边
=sin10*1/2*cos20*cos40
=1/2*sin10cos10cos20cos40/cos10
=(1/2)*8sin10cos10cos20cos40/8cos10
=(1/16)*4sin20cos20cos40/cos10
=(1/16)*2sin40cos40/cos10
=(1/16)*sin80/sin80
=1/16=右边
求证Sin10° *Sin30° *Sin50° *Sin70° =1/16
sin10°sin30°sin50°sin70°=?
sin10°×sin30°×sin50°×sin70°=( ).求详解,
sin10°sin50°-sin50°sin70°-sin70°sin10°=?
sin10°sin30°sin50°sin70°的值为( )
2 sin10*sin30*sin50*sin70=?
求值:sin10°sin50°sin70°sin80°
sin10°×sin50°×sin70°等于多少
求值:sin10°sin50°·sin70°
sin10°sin50°sin70° 怎样化简求值?
正弦函数求值sin10°*sin50°*sin70°
sin10°*sin50°*sin70°等于好多