化简2tan(-α).cos(7π-α)/sin(5π-α)
问题描述：
化简2tan(-α).cos(7π-α)/sin(5π-α)
答
2tan(-α).cos(7π-α)/sin(5π-α)
=2tan(-α).cos(π-α)/sin(π-α)
=2tan(-α).[-cos(α)]/sin(α)
=-2sin(-α)cos(α)/[sin(α)cos(-α)]
=2cos(α)/cos(-α)
=2