Understand the rule first
Imagine folding the shape along a proposed line. Every point, edge and shaded mark must match at the same distance on the other side.
Identify and count lines that divide figures into reflected halves.
Imagine folding the shape along a proposed line. Every point, edge and shaded mark must match at the same distance on the other side.
Counting rotational positions or diagonals that do not produce matching reflected halves.
Reusable method: Imagine folding on the proposed line.Test vertical, horizontal and diagonal folds.
Answer A: 2
Only the vertical and horizontal centre lines work, giving 2.
Quick method: Imagine folding on the proposed line.
Each line can run from a vertex to the opposite side’s midpoint.
Answer B: 3
An equilateral triangle has one symmetry line from each of its three vertices.
Quick method: Imagine folding on the proposed line.
Count vertex-to-vertex and side-midpoint lines.
Answer C: 6
There are three of each type, making 6.
Quick method: Imagine folding on the proposed line.
Test a vertical fold and a horizontal fold.
Answer D: 2
A balanced block H has vertical and horizontal symmetry, giving 2 lines.
Quick method: Imagine folding on the proposed line.
Include both diagonals as well as vertical and horizontal lines.
Answer A: 4
A square has 4 lines of symmetry.
Quick method: Imagine folding on the proposed line.
A regular polygon has one line associated with each vertex.
Answer A: 5
A regular pentagon has 5 lines of symmetry.
Quick method: Imagine folding on the proposed line.
Any diameter can act as a mirror line.
Answer B: infinitely many
Every diameter is a line of symmetry, so there are infinitely many.
Quick method: Imagine folding on the proposed line.
Test a vertical and horizontal fold.
Answer C: 1
A balanced block T has one vertical line of symmetry.
Quick method: Imagine folding on the proposed line.