如图,AB为⊙O的直径,弦CK交AB于P,D为上一点,且∠CPD=∠BPD=60°,连OC、OD.
(1)求证:∠OCK=∠ODP;
(2)若PC=4 , PO=6 , 求S△POD .
(1)求点C的坐标;
(2)连接MG、BC,求证:MG∥BC.
(1)求证:四边形PEQB为平行四边形;
(2)填空:
①当t=多少s时,四边形PBQE为菱形;
②当t=多少s时,四边形PBQE为矩形.