Symmetric
Symmetric – Identical parts facing each other. The simplest type is a mirror.

See metal tick (symmetric) with a mirror. (Mirrors always provide a symmetrical view in reflection.)
Example 1

A circle is symmetrical through any line that divides it perfectly in half.
Example 2

A rectangle is symmetrical about a vertical line through the centre, and a horizontal line through the centre.
Example 3

This triangle is symmetrical about the vertical line passing through its centre.
Example 4

This plane shape is symmetrical about the red line that passes through it.
Example 5

Lines such as the ones above or those on a graph may also be symmetrical.