sin(540°+α)cos(360°-α)/sin(450°+α)tan(900°-α)急!_数学解答

sin(540°+α)cos(360°-α)/sin(450°+α)tan(900°-α)
急!

人气：442 ℃　时间：2020-04-12 19:45:46

解答

sin(540°+α)cos(360°-α)/[sin(450°+α)tan(900°-α)]
=sin(180°+α)cosα/[sin(90°+α)tan(180°-α)]
=-sinαcosα/[-cosα.tanα]
=-sinαcosα/[-sinα]
=cosα