The straight line l passes through two points p 1 (x 1, y 1) p2 (x2, y2) (x 1 ≠ x2).
Therefore, its slope k=(y2-y 1)/(x2-x 1), and if it is substituted into the point inclination formula, Y = K (X-X 1)+Y 1 is obtained.
App application
1. Find its linear equation from two points.
2. Find the area class problem of a triangle surrounded by another point.