NCERT Class 6 Maths Chapter 9
Symmetry
This chapter helps Class 6 CBSE students understand the concept of symmetry in both natural and geometric figures, focusing on line symmetry (reflection) and rotational symmetry. Students learn to identify lines of symmetry in shapes and figures, determine the order of rotational symmetry, and create symmetric patterns. The chapter connects mathematics to art, nature, and design, making it a visually engaging and intuitive topic.
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Key Terms
- Symmetry
- A property of a figure where one part is a mirror image of another part when divided by a line or rotated about a point.
- Line of Symmetry
- A line that divides a figure into two identical mirror-image halves; also called the axis of symmetry.
- Line Symmetry
- A type of symmetry where one half of a figure is a mirror reflection of the other half along a line.
- Rotational Symmetry
- A figure has rotational symmetry if it looks the same after being rotated by less than 360° around a central point.
- Order of Symmetry
- The number of times a figure looks exactly the same during a full 360° rotation.
- Mirror Image
- The reflection of an object in a mirror, which appears as an identical but laterally reversed image.
Frequently Asked Questions
What is line symmetry in Class 6 Maths?▾
A figure has line symmetry if it can be folded along a line so that both halves match exactly. The fold line is called the line of symmetry or axis of symmetry. A square has 4 lines of symmetry, a rectangle has 2, and a circle has infinitely many.
What is rotational symmetry in Class 6 Maths Chapter 9?▾
A figure has rotational symmetry if it looks the same after being rotated by a certain angle less than 360°. The number of times it matches during a full rotation is the order of rotational symmetry. A square has rotational symmetry of order 4 (at 90°, 180°, 270°, 360°).
How many lines of symmetry does a circle have in Class 6 Maths?▾
A circle has infinite lines of symmetry because any diameter of the circle acts as a line of symmetry. Every line through the centre of a circle divides it into two identical semicircles.
How many lines of symmetry does an equilateral triangle have?▾
An equilateral triangle has 3 lines of symmetry. Each line passes from a vertex to the midpoint of the opposite side. The equilateral triangle also has rotational symmetry of order 3 (looks the same at 120°, 240°, and 360°).
Where do we see symmetry in nature in Class 6 Maths?▾
Symmetry is widely found in nature. Butterfly wings, human bodies, flowers (like sunflowers), leaves, and snowflakes all show symmetry. Artists, architects, and designers also use symmetry to create beautiful and balanced patterns and structures.
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