1.AEB=ADB=BEC=90 直径所对角=90 C=C △BEC∽△ADC
2.连接DE
则DEC=ABC C=C ABC相似DEC
AB/DE=BC/EC
弧BD=弧DE BD=DE=1/2BC
即1/2BC*BC =AB*EC
BC²=2AB·CE
1.AEB=ADB=BEC=90 直径所对角=90 C=C △BEC∽△ADC
2.连接DE
则DEC=ABC C=C ABC相似DEC
AB/DE=BC/EC
弧BD=弧DE BD=DE=1/2BC
即1/2BC*BC =AB*EC
BC²=2AB·CE