Three equal point charges, each with a charge of 1.85 μC, are placed at the vertices of an equilateral triangle whose sides are of length 0.550 m. What is the electric potential energy U of the system? (Take as zero the potential energy of the three charges when they are infinitely far apart.) Use ε0 = 8.85×10^−12 (C^2)/(N⋅m^2) for the permittivity of free space.