Page 284 - ICSE Math 7

SYMMETRY, REFLECTION AND ROTATION

Symmetry
A geometrical figure is symmetric if its one half is of the
exactly same size and shape as the other half.

Reflection Rotational Symmetry Rotation
An object and its image are at the If a figure coincides with its image Transformation which rotates all
same distance from a fixed line at least once in a 360° rotation then the points in a plane about a fixed
called a mirror. it has rotational symmetry. point through a given angle

Angle of Rotation
About x-axis About y-axis About Origin The minimum angle through which
A(x, y) → A′(x, – y) A(x, y) → A′(–x, y) A(x, y) → A′(–x, –y) an object or a figure rotates about a
fixed point to coincide with itself

VISUALIZING SOLID SHAPES

Polyhedrons
The solids which are bounded by polygons as their faces

Cube Cuboid Prism Pyramid

Nets of 3D Shapes

Cube Cuboid Cylinder Cone

270