Quadrilateral just means “four sides”

**A Quadrilateral has ****four-sides**, it is **2-dimensional** (a flat shape), **closed** (the lines join up), and has **straight** sides.

- Four sides (edges)
- Four vertices (corners)
- The interior angles add up to
**360 degrees**:

Try drawing a quadrilateral, and measure the angles. They should add to **360°**

- A polygon’s
**diagonals**are line segments from one corner to another, but not the sides.

There are special types of quadrilateral:

Some types are also included in the definition of other types! For example a **square**, **rhombus** and **rectangle** are also ** parallelograms**.

You can find if a shape has a Line of Symmetry by** folding it**.

When the folded part sits perfectly on top (all edges matching), then the fold line is a Line of Symmetry.

Here I have folded a rectangle one way, and **it didn’t work**.

So this is **not** a Line of Symmetry

But when I try it this way, it **does work** (the folded part sits perfectly on top, all edges matching):

So this **is** a Line of Symmetry