RBSE Class 7 Maths Notes Chapter 14 Symmetry

These comprehensive RBSE Class 7 Maths Notes Chapter 14 Symmetry will give a brief overview of all the concepts.

RBSE Class 7 Maths Chapter 14 Notes Symmetry

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

→ If a figure is not identical about a line then it is called asymmetric figure.

→ Regular polygons have equal sides and equal angles. They have multiple (i.e. more than one) lines of symmetry.

→ Each regular polygon has as many lines of symmetry as it has sides.

→ Mirror reflection leads to symmetry, under which the left-right orientation have to be taken care of.

→ 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. Complete rotation is 360°, a half turn means rotation by 180°, a quarter-turn means rotation by 90°.

→ Rotation may be clockwise or anticlockwise.

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

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

→ 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.