∠MON =180°-35°-25° =120°
cosMON =cos120° = -1/2
OM=ON =30 (радиусы)
MN^2 =OM^2 +ON^2 -2OM*ON*cosMON (т косинусов)
MN =√(30^2 +30^2 +2*30*30*(-1/2)) =√(3*30^2) =30√3
