Question

Which of the following is always true about lines of symmetry?

A figure can have only one line of symmetry.
A line of symmetry divides a shape into two equal parts.
A line of symmetry goes through opposite vertices of a figure.
A line of symmetry is a vertical line through the middle of a figure.

Answer 1

Only the second statement is always true:

- A line of symmetry divides a shape into two equal (congruent, mirror-image) parts.

Why the others are false:
- "A figure can have only one line of symmetry." — False. Figures can have 0, 1, 2, 3, 4, or infinitely many lines of symmetry (e.g., circle).
- "A line of symmetry goes through opposite vertices of a figure." — False. Some symmetry lines go through midpoints of opposite sides (e.g., a rectangle) or are diagonal or none at all.
- "A line of symmetry is a vertical line through the middle of a figure." — False. Symmetry lines can be horizontal, diagonal, or at any angle (or multiple lines), not necessarily vertical.