Question

已知sin(π+α)=

1

2

，求sin(π-α)-tan(-α-π)•sin(

π

2

+α)的值．

Answer 1

∵sin(π+α)=

1

2

∴sinα=-

1

2

∴sin(π-α)-tan(-α-π)•sin(

π

2

+α)
=sinα+tanαcosα=2sinα=-1