(1/sin10度)—(根号3/sin80度)=

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(1/sin10度)—(根号3/sin80度)=

1/sin10-sqrt(3)/sin80
=(cos10-sqrt(3)*sin10)/(cos10*sin10)
=4*(cos60*cos10-sin60*sin10)/sin20
=4*cos70/sin20
=4