# Reflection

Reflections are everywhere ... in mirrors, glass, and here in a lake.

... what do you notice ?

Every point is the same distance from the central line !

*... and ...*

The reflection has the same size as the original image.

The central line is called the **Mirror Line**:

## Can A Mirror Line Be Vertical?

Yes. Here my dog "Flame" shows a Vertical Mirror Line (with a bit of photo editing).

In fact Mirror Lines can be in **any direction**.

Imagine turning the top image in different directions:

A reflection is a **flip** over a line

### You can try reflecting some shapes about different mirror lines here:

## "How Do I Do It Myself?"

Just approach it step-by-step. For **each corner** of the shape:

## Labels

It is common to label each corner with letters, and to use a little dash (called a **Prime**) to mark each corner of the reflected image.

Here the original is **ABC** and the reflected image is **A'B'C'**

## Some Tricks

### X-Axis

When the mirror line is the x-axiswe change each (x,y) into

**(x,−y)**

### Y-Axis

When the mirror line is the y-axis

we change each (x,y) into **(−x,y)**

### Fold the Paper

And when all else fails, just fold the sheet of paper along the mirror line and then hold it up to the light !