Given : $$angle$$ AOB = 120° and AB = 10 cm To find : OC = ? Solution : Perpendicular from the centre to the chord bisects the chord, => AC = CB = $$frac{10}{2}=5$$ cm Also, $$angle$$ AOC = $$angle$$ COB = $$frac{120}{2}=60^circ$$ Thus, in $$ riangle$$ BOC, => $$tan(angle COB)=frac{BC}{OC}$$ => $$tan(60^circ)=frac{5}{OC}$$ => $$OC=frac{5}{sqrt3}$$ cm => Ans - (A)