ABC - triunghi isoscel => AB=AC= 18
ABC inscris in cerc => R = BC/2 => BC = 2R = 30 cm
ARIAabc=AB * AC = 18 * 18 = 324 CM
Pabc = AB+AC+BC=56
O - intersectia mediatoarelor => OA' PERPENDICULAR PE AB SI OB' PERPENDICULAL PE AC => AA'OB' - paralelogram=> AA'== OB',AB'==OA'(AA'- JUM. AB, AB' - JUM AC)=> AA'==AB'==OB'==OA'=>AA'=AB'=AB/2=9