如图,△ABC的内切圆I分别切三角形三边于点D,E,F.1.如果角C=60°,那么∠DFE多少度2.如果三角形的三边AC=5cm,AB=7cm,BC=8cm,那么BD为多少3.改变△ABC的形状,△DEF一定是锐角三角形吗,为什么?
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![如图,△ABC的内切圆I分别切三角形三边于点D,E,F.1.如果角C=60°,那么∠DFE多少度2.如果三角形的三边AC=5cm,AB=7cm,BC=8cm,那么BD为多少3.改变△ABC的形状,△DEF一定是锐角三角形吗,为什么?](/uploads/image/z/11580845-5-5.jpg?t=%E5%A6%82%E5%9B%BE%2C%E2%96%B3ABC%E7%9A%84%E5%86%85%E5%88%87%E5%9C%86I%E5%88%86%E5%88%AB%E5%88%87%E4%B8%89%E8%A7%92%E5%BD%A2%E4%B8%89%E8%BE%B9%E4%BA%8E%E7%82%B9D%2CE%2CF.1.%E5%A6%82%E6%9E%9C%E8%A7%92C%3D60%C2%B0%2C%E9%82%A3%E4%B9%88%E2%88%A0DFE%E5%A4%9A%E5%B0%91%E5%BA%A62.%E5%A6%82%E6%9E%9C%E4%B8%89%E8%A7%92%E5%BD%A2%E7%9A%84%E4%B8%89%E8%BE%B9AC%3D5cm%2CAB%3D7cm%2CBC%3D8cm%2C%E9%82%A3%E4%B9%88BD%E4%B8%BA%E5%A4%9A%E5%B0%913.%E6%94%B9%E5%8F%98%E2%96%B3ABC%E7%9A%84%E5%BD%A2%E7%8A%B6%2C%E2%96%B3DEF%E4%B8%80%E5%AE%9A%E6%98%AF%E9%94%90%E8%A7%92%E4%B8%89%E8%A7%92%E5%BD%A2%E5%90%97%2C%E4%B8%BA%E4%BB%80%E4%B9%88%3F)
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