.[1/cos(-α)+cos(180°+ α )]/[1/sin(540°-α)+sin(360°-α)]=tan^3α
问题描述：
.[1/cos(-α)+cos(180°+ α )]/[1/sin(540°-α)+sin(360°-α)]=tan^3α
答
cos(-α)=cosα,cos(180°+ α)= -cosαsin(540°-α)=sinαsin(360°-α)= -sinα所以原式左边=(1/cosα -cosα) / (1/sinα -sinα)=(1-cos²α)/cosα / (1-sin²α)/sinα=(sin²α/cosα) / (cos...