<span><span>Пусть угол DOK=x </span><em><span>NOD=3x,</span><span>3x+x=120 </span><span>,4x=120 </span><span>,x=120:4 </span><span>,x=30 </span></em><span><em><u>,угол DOK=30</u> !!!</em></span></span>