如图所示,物体沿两个半径为R的半圆弧由A到C,则它的位移和路程大小分别是( )
A:4R,4R
B:4R,2R
C:2R,4R
D:2R,2R
已知函数f(x)=23sinxcosx﹣3sin2x﹣cos2x+2.
(1)当x∈0,π2时,求f(x)的值域;
(2)若△ABC的内角A,B,C的对边分别为a,b,c,且满足ba=3,sin2A+CsinA=2+2cos(A+C),求f(B)的值.
发源于中国,流经缅甸、老挝、泰国、柬埔寨、越南,注入南海的河流是( )
The World Wide Web is sometimes jokingly called the World Wide Wait because it ______be very slow.
以下对电与磁的描述存在问题的是( )