Detailed description

Cartesian plane. Solid line joining points A(x1, y1) and B(x2, y2). Dotted line from A to (x2, y1) labelled 'x2x1' above 'run'; dotted line from B to (x2, y1) labelled 'y2 – y1' above 'rise'. Right-angle symbol at point (x2, y1).