化简cos100°cos40°+sin80°sin40°

来源：学生作业帮助网编辑：作业帮时间：2024/05/11 19:12:21

化简cos100°cos40°+sin80°sin40°
化简cos100°cos40°+sin80°sin40°

化简cos100°cos40°+sin80°sin40°
=cos(90+10)cos40+sin(90-10)sin40
=-sin10cos40+cos10sin40
=sin(40-10)
=1/2