Find perpendicular line using points on that line

Question

I have a line (P1, P2), and a point on that line (midpoint). What equation can I used to find the perpendicular line of line (P1, P2), that passes through midpoint. The poin

Answer 1

Coordinates of P1: (x1,y1) Coordinates of P2: (x2,y2)

Coordinates of midpoint: ( (x1+x2)/2 , (y1+y2)/2) Slope of the P1P2 line: (y1-y2)/(x1-x2) Slope of any perpendicular line to P1P2: (x2-x1)/(y1-y2)

Equation of the red line: y - (y1+y2)/2 = ((x2-x1)/(y1-y2))*(x - (x1+x2)/2)

If you have the actual values of coordinates of P1 y P2, then just make a substitution.