Question

sin10°sin30°sin50°sin70°的值等于

Answer 1

sin10°sin50°sin70°
=sin10°*1/2(cos20°-cos120°)
=1/2sin10°(cos20°+1/2)
=1/4(sin30°-sin10°)+1/4sin10°
=1/4sin30°
=1/8

∴sin10°sin30°sin50°sin70°
=1/2*1/8
=1/16

希望我的回答帮得到您，来自【百度懂你】团队，满意的话烦请采纳~O(∩_∩)O~
打字不易，如满意，望采纳。

Answer 2

因为cosx=sin(90-x)
所以原式=sin10*1/2*cos40cos20
=1/2*2sin10cos10cos20cos40/2cos10
=1/4*sin20cos20cos40/cos10
=1/8*sin40cos40/cos10
=1/16*sin80/sin80
=1/16