Class 7 · Chapter 14

Symmetry

Line and rotational symmetry.

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Tip: open the NCERT PDF for the original chapter text alongside the notes here.

Detailed theory

A figure is line-symmetric if it can be folded along a line so both halves match. Different figures have different numbers of axes.

Key concepts & formulas

A figure has line symmetry if it can be folded along a line so both halves match.

A figure has rotational symmetry if it looks the same after rotation by an angle

<360^\circ

Order of rotational symmetry

=

number of times the figure looks the same in one full turn.

Angle of rotation

= \dfrac{360^\circ}{\text{order}}

A square has line symmetry

= 4

and rotational order

= 4