题目

阅读理解Runnerswho encounter visual and auditory distractions (干扰)maybe more likely to suffer leg injuries, according to research by the Associationof Academic Physiatrists in Las Vegas. Runners often seek distraction from thetask at hand. Whether it is music, texting, daydreaming, taking in the sights, orpropping a book up on the treadmill(跑步机), more oftenthan not a distraction is welcome. But, researchers from the University ofFlorida have recently discovered those distractions may lead to injury. DanielHerman, MD, assistant professor at University of Florida, and his teamcondu已知A为三角形的一个内角，函数y=x2cosA-4xsinA+6，对于?x∈R都有y＞0，则角A的取值范围是    ．