已知sin(π+α)=12，求sin(π-α)-tan(-α-π)•sin(π2+α)的值．

题型：解答题难度：一般来源：不详

已知sin(π+α)=

1

2

，求sin(π-α)-tan(-α-π)•sin(

π

2

+α)的值．

答案

∵sin(π+α)=

1

2

∴sinα=-

1

2

∴sin(π-α)-tan(-α-π)•sin(

π

2

+α)
=sinα+tanαcosα=2sinα=-1