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Distance of a Point from a Line (of a point to a line)

What do we mean when we say : 1. Find the shortest distance of a point from a line ? or 2. Find the distance of a point to a line ? They are asking for the same distance. But do you know what that means. Explore the activity below to understand the concept and meaning.

Distance of a Point to a Line

Exploration

What is the distance of point A (7, 6) to the line CD (or distance of point A from the line CD)? Is it the same as the length of the line segment AB What is the length of the line segment AB ?

If we drag point B along on the line CD, is the length AB now changed?

Is there a particular distance that is the shortest between point A at (7, 6) and the line CD? Keep dragging point B until you find the shortest distance. What is the shortest distance ?

What is the angle between AB and CD when the shortest distance of AB is achieved?

Now drag point A to (5, 5). What is the distance of point A from the line CD (using the distance AB)now?

Drag point B on the line CD again. Has the distance of the point B from the line CD changed?

Is there a particular distance that is shortest between point A at (5, 5) and the line CD? What is the shortest distance between A and the line CD?

What is the angle between AB and CD when this occurs?

Conclusion When we ask for the shortest distance of a point (say A) to a line (or distance of a point A from a line) what conditions must be satisfied?