Let ABC be an equilateral triangle with circumcircle of center O and radius R. Point M is exterior to the triangle such that SbSc=SaSb+SaSc, where Sa,Sb,Sc are the areas of triangles MBC,MCA,MAB respectively. Prove that OM≥R.Nguyễn Tiến Lâm area of trianglegeometric inequalitygeometryEquilateralcircumcircleareas