Question: how to calculate the distance between two lines?
Answer: Distance between Two Parallel Lines It is equal to the length of the perpendicular distance from any point to one of the lines. Let N be the point through which the perpendicular or normal is drawn to l1 from M (− c2/m, 0). We know that the distance between two lines is: d =|Ax1 + By1 + C| / (A2 + B2)½.