Compute the perpendicular distance from a point to a line Ax+By+C=0.
The perpendicular distance from point (x₀, y₀) to line Ax+By+C=0 is |Ax₀+By₀+C| / √(A²+B²).
Point-Line Distance
d = |Ax₀ + By₀ + C| / √(A² + B²)
Rearrange: mx − y + b = 0, so A = m, B = −1, C = b.
Yes — distance is always non-negative. It equals zero only when the point lies on the line.