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Reflection
Reflections are everywhere ... in mirrors, glass, and here in a lake.
... what do you notice ? |
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| Every point is the same distance from the central line ! |
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| The reflection has the same size as the original image |
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| The central line is called the Mirror Line ... |
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| ... and it doesn't matter what direction the mirror line goes, the reflected image is always the same size, it just faces the other way: |
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A reflection is a FLIP over a line |
You can try reflecting different shapes about different mirror lines here:
Try it out to see what happens !
Note: If you cannot see this interactive graph, you will need to install "Flash Player"
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How Do I Do It Myself?
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Just approach it step-by-step. For each corner of the shape: |
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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! |
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Labels
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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'
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Some Tricks
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X-Axis
If the mirror line is the x-axis, just change each (x,y) into (x,-y) |
Y-Axis
If the mirror line is the y-axis, just change each (x,y) into (-x,y)
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Fold the Paper
And if all else fails, just fold your sheet of paper along the mirror line and then hold it up to the light !
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