For two linear equations to represent coincident lines, their ratios must be equal. The given equations are:
\[
a_1x + b_1y + c_1 = 0 \quad \text{and} \quad a_2x + b_2y + c_2 = 0
\]
For the lines to coincide, the ratio of the corresponding coefficients of \(x\), \(y\), and the constant term must be the same:
\[
\frac{a_1}{a_2} = \frac{b_1}{b_2} = \frac{c_1}{c_2}
\]
Thus, the condition for coincident lines is that the ratios of the coefficients should be equal.