DISTANCE FROM
A POINT TO A
LINE
Objectives
1. Recall that the distance from a point (x1,y1) to the
line 𝐴𝑥+𝐵𝑦+𝐶=0 is given by the formula
d = 𝐴x1+𝐵y1+𝐶
2 2
√𝐴 +𝐵
2. Use the formula to calculate the distance from a point to a line (the
line may be given in vector form)
The distance from point (x1,y1) to a line (Ax1 + By1 + C = 0),
where both a and b cannot be equal to zero. If line is vertical or
horizontal, then the distance is just the horizontal/vertical
distance.
So, the distance (or perpendicular distance) D, from point P (x1,y1)
to a line L: Ax + By + C = 0 is given by
d = 𝐴x1+𝐵y1+𝐶
2 2
√𝐴 +𝐵
Find the length of perpendicular drawn from point A (1,9)
to the line -5x + 12y + 13 = 0.
Find the distance from the point (3,-4) to line 6x -
8y = 5.
Find the distance from point (2,1) to a line y = 2x + 1
Determine the distance between the origin and the line r =
(1,4) + s (2,1).
ASSIGNMENT:
Find the distance from the point with the given coordinates and
to the line with the given equation.
1. (-1, 5), 3x - 4y -1 = 0
2. (2,5), 5x – 12y = 1
3. 2x + 3y = 6; (7, 6)