作业帮已知tan(π+α)=a²,|cos(π-α)|=-cosα,求1/[cos(π+α)]的值
来源：学生作业帮助网 编辑：作业帮 时间：2024/07/21 10:16:11
![已知tan(π+α)=a²,|cos(π-α)|=-cosα,求1/[cos(π+α)]的值](/uploads/image/z/5189018-50-8.jpg?t=%E5%B7%B2%E7%9F%A5tan%28%CF%80%2B%CE%B1%29%3Da%26%23178%3B%2C%7Ccos%28%CF%80-%CE%B1%29%7C%3D-cos%CE%B1%2C%E6%B1%821%2F%5Bcos%28%CF%80%2B%CE%B1%29%5D%E7%9A%84%E5%80%BC)
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已知tan(π+α)=a²,|cos(π-α)|=-cosα,求1/[cos(π+α)]的值
已知tan(π+α)=a²,|cos(π-α)|=-cosα,求1/[cos(π+α)]的值
已知tan(π+α)=a²,|cos(π-α)|=-cosα,求1/[cos(π+α)]的值
|cos(π-α)|=-cosα>0
所以cos(π+α)=-cosα>0
tan(π+α)=a²=sin(π+α)/cos(π+α)>=0
所以sin(π+α)0
因此 1/[cos(π+α)]=(1+a^4)^(1/2)