Chapter 6: CONSTRUCTIONS AND TILINGS

Math-2 • Class 7

Download PDF

Loading PDF...

Chapter Analysis

Intermediate29 pages • English

Quick Summary

This chapter explores geometric constructions and tiling patterns. It details methods for constructing perpendicular bisectors, angle bisectors, and various polygons using basic geometric tools like a ruler and compass. The chapter also discusses tiling concepts, highlighting how different shapes can tile a plane without gaps or overlaps, including real-world examples like bee hives. Applications of these constructions in historical contexts and in architecture are also elaborated.

Key Topics

  • Perpendicular bisectors
  • Angle bisection
  • Geometric constructions with compass and ruler
  • Tiling with polygons
  • Constructing regular polygons
  • Historical mathematical constructions

Learning Objectives

  • Construct perpendicular bisectors and understand their properties.
  • Learn to bisect various angles using ruler and compass.
  • Understand the concept of tiling a plane with different shapes.
  • Construct various geometric figures and understand their applications.
  • Explore historical approaches to geometric constructions.
  • Apply geometric concepts to solve real-world problems.

Questions in Chapter

When constructing the perpendicular bisector, is it necessary to have the same radius for the arcs above and below XY? Explore this through construction, and then justify your answer.

Page 140

Is it necessary to construct the pairs of arcs above and below XY? Instead, can we construct both the pairs of arcs on the same side of XY?

Page 140

While constructing one pair of intersecting arcs, is it necessary that we use the same radii for both of them? Explore this through construction, and then justify your answer.

Page 140

Recreate this design using only a ruler and compass.

Page 140

Construct at least 4 different angles. Draw their bisectors.

Page 144

Figure it Out: Construct a regular hexagon with a sidelength 4 cm using a ruler and a compass.

Page 153

Additional Practice Questions

How can you construct a 60° angle using only a ruler and a compass?

easy

Answer: A 60° angle can be constructed by first drawing an equilateral triangle, where each angle measures 60°.

What regular polygons can tile a plane and why?

medium

Answer: Squares, equilateral triangles, and regular hexagons can tile a plane because their interior angles are divisors of 360°, allowing them to fit together without gaps.

Describe a method to bisect an angle using geometric constructions.

medium

Answer: To bisect an angle, use a compass to draw an arc that intersects both arms of the angle, then draw arcs of equal radius from those points. The intersection of the arcs is on the angle bisector.

Explain how tangram pieces can be used to demonstrate tiling.

medium

Answer: Tangram pieces, originated from China, can be rearranged to cover a defined area without gaps, showcasing practical tiling on a two-dimensional plane.

What are the applications of perpendicular bisectors in real-world scenarios?

easy

Answer: Perpendicular bisectors are used in various fields like engineering and architecture to ensure symmetry and accuracy in designs. They are crucial in navigation systems for triangulation.