(cos15°-cos75°)(sin75°+sin15°)怎么化简?

来源:学生作业帮助网 编辑:作业帮 时间:2024/04/29 12:41:25
(cos15°-cos75°)(sin75°+sin15°)怎么化简?

(cos15°-cos75°)(sin75°+sin15°)怎么化简?
(cos15°-cos75°)(sin75°+sin15°)怎么化简?

(cos15°-cos75°)(sin75°+sin15°)怎么化简?
(cos15°-cos75°)(sin75°+sin15°)
=(sin75-cos75)(sin75+cos75)
=sin²75-cos²75
=-(cos²75-sin²75)
=-cos(2×75)
=-cos150
=√3/2

(cos15°-cos75°)(sin75°+sin15°)
=(cos15°-sin15°)(cos15°+sin15°)
=cos²15°-sin²15°
=cos30°
=√3/2