Reflection

Reflections are everywhere ... in mirrors, glass, and here in a lake.
... what exercise yous notice ?

Reflection in Lake

Reflection Illustrated

Every point is the same altitude from the key line !

... and ...

The reflection has the same size as the original paradigm

The cardinal line is called the Mirror Line ...

reflection up-down

flame mirror center line

Tin can A Mirror Line Be Vertical?

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

In fact Mirror Lines can be in whatever management.
Imagine turning the top paradigm in different directions:

Left-Right Reflection 75 Degrees Reflection

A reflection is a flip over a line

You can try reflecting some shapes about dissimilar mirror lines here:

How Do I Do It Myself?

Just approach information technology step-by-stride. For each corner of the shape:

Labels

Mirror Image Prime

It is common to characterization each corner with letters, and to use a piffling nuance (chosen a Prime number) to mark each corner of the reflected image.

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

Some Tricks

Reflect About X Axis

X-Axis

When the mirror line is the 10-axis
we change each (ten,y) into (x,−y)

Reflect About Y Axis

Y-Axis

When the mirror line is the y-axis
we change each (ten,y) into (−x,y)

Fold the Paper

And when all else fails, but fold the sheet of newspaper along the mirror line and and so hold it up to the light !