NCERT Exemplar Solutions
Class 6 - Mathematics - Unit 9: Symmetry and Practical Geometry - Fill in the Blanks

Question 21

What is a line of symmetry?

A line of symmetry divides a shape into two exact mirror halves.

If you fold the shape on this line, both parts match perfectly.

Understand a rectangle

A rectangle has opposite sides equal and all angles are right angles.

Try the fold test:

• Fold through the middle vertically (top to bottom through the center). The two halves match.
• Fold through the middle horizontally (left to right through the center). The two halves match.
• Fold along a diagonal. The corners do not overlap exactly for a general rectangle. ❌

So, a rectangle has:

( ext{Rectangle:} )

( quad ext{Lines of symmetry} = 2 )

Understand a square

A square has all sides equal and all angles are right angles.

Try the fold test:

• Fold through the middle vertically. Matches.
• Fold through the middle horizontally. Matches.
• Fold along the first diagonal. Matches.
• Fold along the second diagonal. Matches.

So, a square has:

( ext{Square:} )

( quad ext{Lines of symmetry} = 4 )

Compare the numbers

( ext{Rectangle: } 2 )

( ext{Square: } 4 )

( 2 eq 4 Rightarrow ) The numbers are unequal.