Three equal point charges, each with a charge of 1.25 μC, are placed at the vertices of an equilateral triangle whose sides are of length 0.600 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.