Ex.14.3 Q4 Symmetry - NCERT Maths Class 7

Question

Fill in the blanks – Shape; Centre of Rotation; Order of Rotation; Angle of Rotation; for each of the figures respectively.

Shape	Centre of Rotation	Order of Rotation	Angle of Rotation
Square
Rectangle
Rhombus
Equilateral Triangle
Regular Hexagon
Circle
Semi-circle

Text Solution

What is known?

Shapes

What is unknown?

Centre of rotation, order of rotation and angle of rotation.

Reasoning:

Centre of rotation: In case of polygon centre of rotation is intersecting point of diagonals and in case of circle centre of rotation is centre of the circle.

Order of rotation: In case of regular polygon order of rotation is always equals to the number of sides and in case of circle order of rotation is infinite.

Angle of rotation: In case of regular polygon angle of rotation is always equals to the measurement of one angle and in case of circle angle of rotation is at every point.

Steps:

Shape	Centre of Rotation	Order of Rotation	Angle of Rotation
Square	Intersecting points of diagonals	\(4\)	90°
Rectangle	Intersecting points of diagonals	\(2\)	\(180^\circ\)
Rhombus	Intersecting points of diagonals	\(2\)	\(180^\circ\)
Equilateral Triangle	Intersecting points of diagonals	\(3\)	\(120^\circ\)
Regular Hexagon	Intersecting points of diagonals	\(6\)	\(60^\circ\)
Circle	Mid- point of diameter	Infinite	At every point
Semi-circle	Mid- point of diameter	\(1\)	\(360^\circ\)