设θ是第三象限角且|cos(θ/2)|=-cos(θ/2),则θ/2是第___________象限角
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![设θ是第三象限角且|cos(θ/2)|=-cos(θ/2),则θ/2是第___________象限角](/uploads/image/z/328114-10-4.jpg?t=%E8%AE%BE%CE%B8%E6%98%AF%E7%AC%AC%E4%B8%89%E8%B1%A1%E9%99%90%E8%A7%92%E4%B8%94%7Ccos%28%CE%B8%2F2%29%7C%3D-cos%28%CE%B8%2F2%29%2C%E5%88%99%CE%B8%2F2%E6%98%AF%E7%AC%AC___________%E8%B1%A1%E9%99%90%E8%A7%92)
设θ是第三象限角且|cos(θ/2)|=-cos(θ/2),则θ/2是第___________象限角
设θ是第三象限角且|cos(θ/2)|=-cos(θ/2),则θ/2是第___________象限角
设θ是第三象限角且|cos(θ/2)|=-cos(θ/2),则θ/2是第___________象限角
∵θ是第三象限角
∴π+2kπ<θ<3π/2+2kπ,k∈Z
∴π/2+kπ<θ/2<3π/4+kπ,k∈Z
∴θ/2是第二或四象限角
∵|cos(θ/2)|=-cos(θ/2)
∴cos(θ/2)<0
∴θ/2是第二象限角