sin50°(1+√3 tan10°)=sin50(cos10+√3 sin10)/cos10=2sin50(cos10*1/2+√3/2*sin10)/(cos10)=2sin50(cos10sin30+cos30sin10)/(cos10)=2sin50sin(30+10)/(cos10)=sin100/(cos10)=cos10/(cos10)=1