A.{kπ+π/2,(k+1)π}
B.{2(k+1)π,2kπ+3π/2}
C.{2kπ+π/4,2kπ+3π/2}
D.{kπ+π/4,(k+1)π}
A.{kπ+π/2,(k+1)π}
B.{2(k+1)π,2kπ+3π/2}
C.{2kπ+π/4,2kπ+3π/2}
D.{kπ+π/4,(k+1)π}
B
只有在第三象限,负sinx 和负cosx是正的
解:sinx≤0,cosx≤0
表示第三象限和坐标轴的负半轴
即x∈[2kπ+π,2kπ+3π/2](k∈Z)
B貌似有错
2(k+1)π>2kπ+3π/2