化简COS8°-SIN17°SIN9°/COS9°
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/11 06:30:33
![化简COS8°-SIN17°SIN9°/COS9°](/uploads/image/z/10153721-65-1.jpg?t=%E5%8C%96%E7%AE%80COS8%C2%B0-SIN17%C2%B0SIN9%C2%B0%2FCOS9%C2%B0)
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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°
则:
原式=[cos17°cos9°]/[cos9°]=cos17°