题目内容
如图,AB为⊙O的直径,点C在⊙O上,∠A=40°,则∠B等于
A.80°
B.60°
C.50°
D.40°
如图,AB为⊙O的直甲径,PD切⊙O于点C,交AB的延长线于D,且CO=CD,则∠PCA=
A.60°
B.65°
C.67.5°
D.75°