Detailed description
Line x and triangle ABC above it. A(x1, y1), B(x2, y2) and C(x3, y3). Lines AP, CR and BQ perpendicular to line x and P, R, Q are points on x.
Coordinate geometry
Line x and triangle ABC above it. A(x1, y1), B(x2, y2) and C(x3, y3). Lines AP, CR and BQ perpendicular to line x and P, R, Q are points on x.