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°...