化简COS8°-SIN17°SIN9°/COS9°
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/01 21:17:48
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化简COS8°-SIN17°SIN9°/COS9°
化简COS8°-SIN17°SIN9°/COS9°
化简COS8°-SIN17°SIN9°/COS9°
∵cos8°=cos(17°-9°)=cos17°cos9°+sin17°sin9°
∴cos8°-sin17°sin9°=cos17°cos9°
∴(cos8°-sin17°sin9°)/cos9°=cos17°cos9°/cos9°=cos17°
最后答案为:cos17°
COS8°-SIN17°SIN9°/COS9°=(COS8°+cos26°/2-cos8°/2)/cos9°=(cos26°/2+cos8°/2)cos9°
=cos17°*cos9°/cos9°=cos17°