解tan675°+1/tan765°-sin(-5π/2)+1/cos(-23π/6)=tan(720°-45°)+1/tan(720°+45°)+sin(5π/2)+1/cos(23π/6)=tan(-45°)+1/tan(45°)+sin(2π+π/2)+1/cos(4π-π/6)=-tan(45°)+1/1+sin(π/2)+1/cos(-π/6)=-...