The distance of the point from the line is given by
Let be the inclination of the line as shown in the given diagram, and then its slope is given as
Squaring both sides of the above value of the slope, we get
Draw a perpendicular line from point to the X-axis intersecting the line at point . Since the abscissa of is the same as that of , the coordinates of point are , . In the triangle , and , so
Since the distance should be positive, we must take the modulus of the right side of the above equation, i.e.
Putting the value of from equation (i) in equation (ii), we get
Since the point lies on the line , then
Putting this value in equation (iii), we get
Example: Find the distance of the point from the line .
Since the given point is , so
Since the given line is , so
The required distance is