Notes / Analytic Geometry Distance formula Theorem 1.1 of Analytic Geometry · Read in context · PDF Theorem 1.1 (Distance formula). The distance between \(P_1(x_1, y_1)\) and \(P_2(x_2, y_2)\) is \[ P_1P_2 = \sqrt {(x_2 - x_1)^2 + (y_2 - y_1)^2}. \]