# Chapter 14 Symmetry Class 7 Notes Maths

Chapter 14 Symmetry Class 7 Notes Maths is available here which will make entire memorizing process effortless and entertaining. NCERT Notes becomes a vital resource for all the students to self-study from NCERT textbooks carefully. Revision Notes for Class 7 will allows the students to evaluate their learning immediately.Â A student will enjoy the revising process and make themselves capable of retaining more information so they can excel in the exams. You will findÂ NCERT Solutions for Class 7 Chapter 14 Maths that can make things a little easier for you.

Line Symmetry

â€¢ A figure has a line symmetry, if there is a line about which the figure may be folded so that the two parts of the figure will coincide.

Lines of symmetry for regular polygons

â€¢ A polygon is said to be regular if all its sides are of equal length and all its angles are of equal measure.Â

â€¢ An equilateral triangle is regular because each of its sides has same length and each of its angles measures 60Â°.

â€¢ A square is also regular because all its sides are of equal length and each of its angles is a right angle (i.e., 90Â°). Its diagonals are seen to be perpendicular bisectors of one another.

â€¢ If a pentagon is regular, naturally, its sides should have equal length.Â The measure of each of its angles is 108Â°.

â€¢ A regular hexagon has all its sides equal and each of its angles measures 120Â°.

Rotational symmetry

â€¢ Rotation turns an object about a fixed point. This fixed point is the centre of rotation. The angle by which the object rotates is the angle of rotation.

â€¢ A half-turn means rotation by 180Â°; a quarter-turn means rotation by 90Â°. Rotation may be clockwise or anticlockwise.

â€¢ If, after a rotation, an object looks exactly the same, we say that it has a rotational symmetry.

â€¢ In a complete turn (of 360Â°), the number of times an object looks exactly the same is called the order of rotational symmetry. The order of symmetry of a square, for example, is 4 while, for an equilateral triangle, it is 3.

Line Symmetry and Rotational Symmetry

â€¢ Some shapes have only one line of symmetry, like the letter E; some have only rotational symmetry, like the letter S; and some have both symmetries like the letter H.

Line Symmetry and Mirror Reflection

â€¢ A shape has line symmetry when one half of it is the mirror image of the other half.

â€¢ Mirror reflection leads to symmetry, under which the left-right orientations have to be taken care of.
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