The idea in brief. The new line passes through the given point and meets the given line at a right angle. Your line must pass through the given point as well as make a right angle. In the lesson. In the previous lesson, you learned that perpendicular lines meet at a right angle. Today, we will draw a line through a point, perpendicular to another line. The new line must go through the point. It must meet the first line at a right angle.
Lesson video, with the working
Draw a perpendicular
3 min 29 s
The film teaches 3 questions in turn. Each question shows first; its working is written as the film explains it.
Move the set square along AB until its perpendicular edge passes through C.
Draw along that edge through C.
Mark the right angle at the meeting point.
Ans: A straight line through C, perpendicular to AB, with a right-angle mark.
Answer: A straight line through C, perpendicular to AB, with a right-angle mark.
For parents
How do you go about drawing perpendicular lines with a set square in P3?
This Primary 3 lesson moves from spotting perpendicular lines to drawing one.
What your child learns here
This Primary 3 lesson moves from spotting perpendicular lines to drawing one. With a ruler and a set square, your child draws a line through a marked point that meets a given line at a right angle.
A perpendicular line meets the given line at a right angle.
The ruler stays still along the given line and guides the set square.
The set square's right-angle corner rests on the ruler and slides until its edge reaches the point.
The finished line passes through the point and carries a right-angle mark.
Does the answer make sense?
A finished drawing must pass through the marked point and make a right angle with the given line where the two meet. The corner of your child's set square should sit snugly in that corner with no gap along either line, and the small right-angle square belongs exactly there.
How to practise these questions
The Basic questions practise placing the set square along the line and drawing the perpendicular. The Intermediate questions add points that lie away from the line or lines at a slant, which need the ruler and set square used together. When a perpendicular drawing goes astray, play its solution film and redo it later from Revision.
Questions parents ask
Is drawing perpendicular lines in the P3 syllabus? Yes. The Primary 3 syllabus lists drawing perpendicular and parallel lines, and this page covers the perpendicular one with a ruler and a set square.
Which set square should my child use? Either set square in a standard school geometry set has a right-angle corner, so either works. What matters is that the right-angle corner sits against the ruler.
Can the point be on the line itself? Yes. The same steps work whether the point is on the line, above it or below it. The set square slides along the ruler until its edge reaches the point.
