一个圆的内接四边形有什么性质
人气:163 ℃ 时间:2020-05-13 16:54:59
解答
如四边形ABCD内接于圆O,延长AB至E,AC、BD交于P,则A+C=180度,B+D=180度,
角ABC=角ADC(同弧所对的圆周角相等).
角CBE=角D(外角等于内对角)
△ABP∽△DCP(三个内角对应相等)
AP*CP=BP*DP(相交弦定理)
AB*CD+AD*CB=AC*BD(托勒密定理)
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