Maths Symmetry part 9 (Symmetry in Regular Polygons) CBSE Class 6 Mathematics VI  Summary and Q&A
TL;DR
Regular polygons have equal sides and angles, and the number of lines of symmetry is equal to the number of sides in the polygon.
Questions & Answers
Q: What is a regular polygon?
A regular polygon is a closed figure with equal sides and equal angles. It is made up of line segments, and all of its sides and angles are of equal length.
Q: How many lines of symmetry does an equilateral triangle have?
An equilateral triangle has three lines of symmetry. These lines are drawn from each vertex to the midpoint of the opposite side, dividing the triangle into two equal halves.
Q: What is the difference in the number of lines of symmetry between an equilateral triangle and an isosceles triangle?
An equilateral triangle has three lines of symmetry because all of its sides are equal, making it a regular polygon. However, an isosceles triangle has only one line of symmetry because only two of its sides are equal.
Q: How many lines of symmetry does a regular hexagon have?
A regular hexagon has six lines of symmetry. Three of these lines are drawn from the opposite vertices, and the other three are drawn from the midpoints of the opposite sides.
Summary & Key Takeaways

Regular polygons are closed figures with equal sides and equal angles.

Examples of regular polygons include equilateral triangles, squares, and regular pentagons.

The number of lines of symmetry in a regular polygon is equal to the number of sides it has.