求值：sin10°sin50°sin70°sin80°
问题描述：
求值：sin10°sin50°sin70°sin80°
答
题目错了吧sin80应该是sin30sin10sin30sin50sin70=cos10sin10sin30sin50sin70/cos10=1/2sin20sin70sin30sin50/cos10=1/4sin40sin50sin30/cos10=1/8sin80sin30/cos10=1/8cos10sin30/cos10=1/8sin30=1/8*1/2=1/16...