This is sometimes called a 'mirror line ... would show the whole shape. • An isosceles triangle has 1 line of symmetry. • A square has 4 lines of symmetry. • A circle has unlimited lines ...

The unusually shaped mirror and sword of more than 2 meters were discovered at the Tomiomaruyama kofun, Japan’s largest round kofun, which was created in the second half of the fourth century.