百度作业网函数 (4 17:58:40)
来源：学生作业帮 编辑：百度作业网作业帮 分类：数学作业 时间：2024/04/30 04:30:30
函数 (4 17:58:40)
sin163°sin223°+sin253°+sin313°=
sin163°sin223°+sin253°+sin313°=
题目应该是
sin163°sin223°+sin253°sin313°,?
sin163°sin223°+sin253°sin313°
=-sin(180-°163°)sin(223°-180°)+sin(253°-180°)sin(360°-313°)
=-sin17°sin23°+sin73°sin47°
=-sin17°cos47°+cos17°sin47°
=sin(47°-17°)
=sin30°
=1/2
sin163°sin223°+sin253°sin313°,?
sin163°sin223°+sin253°sin313°
=-sin(180-°163°)sin(223°-180°)+sin(253°-180°)sin(360°-313°)
=-sin17°sin23°+sin73°sin47°
=-sin17°cos47°+cos17°sin47°
=sin(47°-17°)
=sin30°
=1/2