Question

sin10度sin50度sin70度=?

我化简出一个式子...然后不会做了

大家帮我看看
谢谢

Answer 1

sin10sin50sin70=2cos10sin10*cos40*cos20/(2cos10)
=sin20cos20cos40/(2cos10)
=0.5sin40cos40/(2cos10)
=0.25sin80/(2cos10)
=1/8