Ruler & Compass Construction Toolkit നിർമിതികൾ
Half of Chapter 3 is drawing: dividing lines, drawing parallels through given points, building triangles and squares with a compass. Every construction in the chapter is made from the ten small moves on this page. Watch each one, then do it on paper with a sharp pencil.
📖 Your tools
- Ruler (scale): to draw straight lines and measure. Compass: to copy a length and to draw arcs. Set squares (two triangles, 45° and 30°–60°): to draw right angles and, by sliding, parallel lines. Protractor: angles.
- In the animations a small red arc is a compass mark and the orange triangle is a set square.
1. Copy a length with the compass
🎬 (a) Make AB equal to a given PQ
2. Perpendiculars ലംബം
🎬 (b) Perpendicular at a point P on a line – compass, then set square
🎬 (c) Perpendicular from a point Q to a line
3. A parallel line through a point
This is the move the chapter uses most. The textbook's way is with two set squares (or a set square and a ruler); the compass way copies a corresponding angle.
🎬 (d1) Sliding a set square along a ruler
🎬 (d2) With a compass: copy a corresponding angle
4. Equal steps along a ray
🎬 (e) A slanted ray with equal compass steps
5. Triangles, squares and hexagons
🎬 (f) A triangle from three sides: arcs for the third vertex
🎬 (g) Equilateral triangle on a segment
🎬 (h) Square on a segment
🎬 (i) Regular hexagon: step the radius around a circle
6. Perpendicular bisector and midpoint
🎬 (j) Find the midpoint of AB without measuring
⚠️ Common mistakes
- Changing the compass opening half-way through a set of equal steps or arcs. Tighten the screw and hold the compass by its top.
- Letting the set square drift while sliding: keep the ruler pressed firmly and move only the set square.
- Measuring from the ruler's edge instead of from the 0 mark.
- Arcs that are too short to meet – draw generous arcs, and let construction lines stay (lightly) on the page; examiners want to see them.
7. Check yourself
🧭 Summary
- Compass: copy lengths, mark equal steps, draw arcs that meet to locate a point.
- Perpendicular at or from a point: equal arcs on the line, then arcs that cross; or use a set square.
- Parallel through a point: slide a set square along a ruler, or copy a corresponding angle.
- Triangle from three sides, equilateral triangle, square, hexagon (side = radius) – all from arcs.
- Perpendicular bisector: two pairs of arcs of the same radius from the two ends.