__maths__>__Construction / Practical Geometry (basics)__>__Secondary Elements of Practical Geometry__### Perpendicular through a point on a line

In this page, a short and to-the-point overview of constructing a perpendicular through a point on a line is provided.

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Which of the following have sides or edges that are perpendicular?

- protractor
- set squares
- set squares

The answer is "set squares"

Given line `bar(AB)` and a point `P` on the line. Place the vertex of perpendicular edges of a set-square with one edge on the given line `bar(AB)`. Construct the line along the other perpendicular edge of the set-square.

**Perpendicular through a point on a line** : Use the perpendicular edges of a set square, one edge on the given line and the perpendicular-vertex on the given point. Construct a line along the other perpendicular edge.

Which of the following methods can be used to construct a perpendicular through a point on a line?

- method to construct perpendicular bisector using a compass
- method to measure `90^@` angle using a protractor
- either one of the above
- either one of the above

The answer is "either one of the above"

**Perpendicular through a point on a line** : Use a compass to mark points `L` and `M` on the line that are in equal distance from the given point `P`. Construct the perpendicular bisector of `bar(LM)`.

**Perpendicular through a point on a line** : Place the protractor with origin on the given point and the base-line on the given line. Mark a point on `90^@` angle and draw a line through the given point and the marked point.

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