Номер 250 помогите плиз

[latex] frac{1}{sin170} - frac{sqrt3}{sin100} = frac{1}{sin(180-10)} -frac{sqrt3}{sin(90+10)} =\\= frac{1}{sin10} -frac{sqrt3}{cos10} = frac{cos10-sqrt3sin10}{sin10cdot cos10} = frac{2(frac{1}{2}cos10-frac{sqrt3}{2}sin10)}{frac{1}{2}sin20} =\\= frac{2(sin30cdot cos10-cos30cdot sin10)}{frac{1}{2}sin20} = frac{4cdot sin(30-10)}{sin20} = frac{4cdot sin20}{sin20} =4[/latex]