计算:cos86°cos34°+sin86°sin214°
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/27 09:53:37
![计算:cos86°cos34°+sin86°sin214°](/uploads/image/z/2502494-62-4.jpg?t=%E8%AE%A1%E7%AE%97%EF%BC%9Acos86%C2%B0cos34%C2%B0%2Bsin86%C2%B0sin214%C2%B0)
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计算:cos86°cos34°+sin86°sin214°
计算:cos86°cos34°+sin86°sin214°
计算:cos86°cos34°+sin86°sin214°
用诱导公式知道sin214°=sin(180°+34°)= - sin34°
那么原式=cos86°cos34°-sin86°sin34°
=cos(86°+34°)
=cos120°
= -0.5