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?
In fact Mirror Lines can be in any direction.
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:
|1. Measure from the point to the mirror line (must hit the mirror line at a right angle)||2. Measure the same distance again on the other side and place a dot.||3. Then connect the new dots up!|
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'
X-AxisWhen the mirror line is the x-axis
we change each (x,y) into (x,−y)
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 !