Question

化简：sin(θ?5π)cos(?π2?θ)cos(8π?θ)sin(θ?3π2)sin(?θ?4π)=______

化简：sin(θ?5π)cos(?π2?θ)cos(8π?θ)sin(θ?3π2)sin(?θ?4π)=______．

Answer 1

式子=

?sin(π?θ)cos( π 2 +θ)cos(?θ)

sin( 3π 2 ?θ)sin(θ+4π)

=

sinθsinθcosθ

?cosθsinθ

=-sinθ，
故答案为：-sinθ．