大师作文网求值：sin10sin30sin50sin70
来源：学生作业帮 编辑：大师作文网作业帮 分类：数学作业 时间：2024/11/12 22:37:18
求值：sin10sin30sin50sin70
sin10sin30sin50sin70 =
1/2 * sin10 * sin50 * sin70 =
1/2 * sin10 * cos20 * cos 40 =
1/2 * cos10 * sin10 * cos20 * cos 40 / cos10 =
1/4 * sin20 * cos20 * cos40 / cos10 =
1/8 * sin40 * cos40 / cos10 =
1/16 * sin80 / cos10 =
1/16 * cos10 / cos10 =
1/16
1/2 * sin10 * sin50 * sin70 =
1/2 * sin10 * cos20 * cos 40 =
1/2 * cos10 * sin10 * cos20 * cos 40 / cos10 =
1/4 * sin20 * cos20 * cos40 / cos10 =
1/8 * sin40 * cos40 / cos10 =
1/16 * sin80 / cos10 =
1/16 * cos10 / cos10 =
1/16