e = c/a = 1/2 ,∴a^2 = 4c^2 ,b^2 = 3c^2 ,椭圆方程化为：3c^2x^2 + 4c^2y^2 = 12c^4化简得：3x^2 + 4y^2 = 12c^2 ,联立切线方程得：4x^2 - 8x + 16 - 12c^2 = 0再由△ = 0 ,解得c = 1 ,a = 2∴椭圆方程：(x^2/4) +...