如图,⊙O是△ABC的外接圆,且AB=AC,点D在弧BC上运动,过点D作DE∥BC,DE交AB的延长线于点E.(1)求证:∠ADB=∠E.(2)当点D运动到什么位置时,DE是⊙O的切线?请说明理由.(3)当AB=5,BC=6时,求⊙O的半径
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![如图,⊙O是△ABC的外接圆,且AB=AC,点D在弧BC上运动,过点D作DE∥BC,DE交AB的延长线于点E.(1)求证:∠ADB=∠E.(2)当点D运动到什么位置时,DE是⊙O的切线?请说明理由.(3)当AB=5,BC=6时,求⊙O的半径](/uploads/image/z/8504648-8-8.jpg?t=%E5%A6%82%E5%9B%BE%2C%E2%8A%99O%E6%98%AF%E2%96%B3ABC%E7%9A%84%E5%A4%96%E6%8E%A5%E5%9C%86%2C%E4%B8%94AB%3DAC%2C%E7%82%B9D%E5%9C%A8%E5%BC%A7BC%E4%B8%8A%E8%BF%90%E5%8A%A8%2C%E8%BF%87%E7%82%B9D%E4%BD%9CDE%E2%88%A5BC%2CDE%E4%BA%A4AB%E7%9A%84%E5%BB%B6%E9%95%BF%E7%BA%BF%E4%BA%8E%E7%82%B9E.%EF%BC%881%EF%BC%89%E6%B1%82%E8%AF%81%EF%BC%9A%E2%88%A0ADB%3D%E2%88%A0E.%EF%BC%882%EF%BC%89%E5%BD%93%E7%82%B9D%E8%BF%90%E5%8A%A8%E5%88%B0%E4%BB%80%E4%B9%88%E4%BD%8D%E7%BD%AE%E6%97%B6%2CDE%E6%98%AF%E2%8A%99O%E7%9A%84%E5%88%87%E7%BA%BF%3F%E8%AF%B7%E8%AF%B4%E6%98%8E%E7%90%86%E7%94%B1.%EF%BC%883%EF%BC%89%E5%BD%93AB%3D5%2CBC%3D6%E6%97%B6%2C%E6%B1%82%E2%8A%99O%E7%9A%84%E5%8D%8A%E5%BE%84)
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