A regular octagon has 10 lines of symmetry.
Why the statement is false
Number of sides = (8)
So, lines of symmetry = (n)
Here, (n = 8 Rightarrow) lines of symmetry = (8)
Visual way to remember
Total = (4 + 4 = 8)
Conclusion
A regular octagon has (8) lines of symmetry, not (10). Therefore, the statement is false.