sin50°(1+√3tan10°)=2sin50°(1/2+√3/2tan10°)=2sin50°(1/2cos10°+√3/2sin10°)/cos10°=2sin50°(sin30°cos10°+cos30°sin10°)/cos10°=2sin50°sin40°/cos10°=2cos40°sin40°/cos10°=sin80°/cos10...