A:①②③
B:①②④
C:③④
D:①②
如图在△ABC中,∠C=90°,BE是∠CBD的平分线,DE⊥BE交AB于点D,圆O是△BDE外接圆.
(Ⅰ)求证:AC是圆O的切线;
(Ⅱ)如果AD=6,AE=62,求BC的长.
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