—He works in a factory.
A:How
B:What
C:Where
D:Who
⑴five ____ A.
⑵six ____ B.
⑶one and three ____ C.
⑷fifteen ____ D.
⑸sixteen ____ E.
如图,已知AD是△ABC的角平分线,⊙O经过A、B、D三点,过点B作BE∥AD,交⊙O于点E,连接ED.
(1)求证:ED∥AC;
(2)连接AE,试证明:AB•CD=AE•AC.