（1）
sin(2π−α)cos(π+α)cos(
3π
2+α)cos(
13π
2−α)
cos(π−α)sin(3π−α)sin(−π−α)sin(
9π
2+α)=−
sinαcosαsinαsinα
cosαsinαsinαcosα=-tanα．
（2）sin
25π
6+cos
23π
3+tan(−
25π
4)+sin
4π
3
=sin(4π+
π
6)+cos(8π−
π
3)+tan(−6π−
π
4)+sin(π+
π
3)
=sin
π
6+cos(−
π
3)+tan(−
π
4)−sin
π
3
=
1
2+
1
2−1−
3
2
=-
3
2．