篮球的单价是____.
A. This is a big ship. B. It's a book about London.
C. London is a big city. D. It's Buckingham Palace.
E. My house is very small, but it's beautiful.
如图,已知AB是⊙O的直径,点C、D在⊙O上,∠D=60°.
(1)求∠BAC的度数;
(2)当BC=4时,求劣弧AC的长.