NCERT Solutions for Class 7 Maths Chapter 14: Symmetry

When a figure is folded in two halves such that both the sides are identical, the figure is known as symmetrical, and this phenomenon is known as symmetry. Here you will learn about reflection symmetry, rotational symmetry, observation of rotational symmetry of the 2D object. In Ex 14.1 topic to be learned is lines of symmetry for the regular polygon. A polygon is defined as a closed figure made up of line segments. A polygon is regular when all the sides are of equal length, and all its angles are of equal measure. In Ex 14.2, students learn about Rotational symmetry. If a given figure can be rotated less than 360 degrees around a point such that it considers itself, it has rotational symmetry.

The fixed point where rotation occurs is called the centre of rotation and the angle through which the body takes a turn is the angle of rotation. A full turn rotation means rotation by 360 degrees. A half-turn rotation means rotation by 180 degrees and a quarter turn means rotation by 90 degrees. In Ex 14.3, you will learn about line symmetry and rotational symmetry. Some shapes have both line symmetry and rotational symmetry, like squares, equilateral triangles, and a regular polygon. Some of the topics and subtopics of this chapter are:

• Lines of symmetry for regular Polygons
• Point symmetry
• Rotational symmetry