化简:[sin(﹣α)cos(π-α)]∕[tan(π+α)sin﹙3π/2+α)]

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化简:[sin(﹣α)cos(π-α)]∕[tan(π+α)sin﹙3π/2+α)]

化简:[sin(﹣α)cos(π-α)]∕[tan(π+α)sin﹙3π/2+α)]
化简:[sin(﹣α)cos(π-α)]∕[tan(π+α)sin﹙3π/2+α)]

化简:[sin(﹣α)cos(π-α)]∕[tan(π+α)sin﹙3π/2+α)]
[sin(﹣α)cos(π-α)]∕[tan(π+α)sin﹙3π/2+α)]
=[(﹣sinα)(-cosα)]∕[tanα﹙-cosα)]
=-sinαcosα∕[tanαcosα]
=-sinα/tanα
=-cosα

[sin(﹣α)cos(π-α)]∕[tan(π+α)sin﹙3π/2+α)]
=[(-sinα)*(-cosα)]∕[tanα*cosα]
=cosα