Compute a line slope, inclination angle and intercept from two points.
由两点坐标求直线斜率。
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Slope | k = (y2 - y1)/(x2 - x1), provided x1 ≠ x2 | ISO 80000-2:2019, Quantities and units - Part 2: Mathematics |
| Relation to the inclination angle | k = tan(theta), where theta is the inclination from the positive x-axis | ISO 80000-2:2019, Quantities and units - Part 2: Mathematics |
| Parallel and perpendicular | Parallel lines have k1 = k2; perpendicular lines have k1 · k2 = -1 | Descartes R., La Geometrie (1637) |
| Point-slope form | y - y1 = k · (x - x1) | ISO 80000-2:2019, Quantities and units - Part 2: Mathematics |